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M31 New alleles of pfmdr1 and other markers of P. We present evidence that, since the adoption of ACT-based treatment policies throughout the region, new 40 forms of many of these genes have become apparent.

The possible origins of these alleles, and the potential contribution of new parasite genotypes to the evolution of resistance to ACTs, will be discussed.

The analytical performance of the device was evaluated in the laboratory. The validity of the MOT device was assessed on measurements on live parasitized erythrocytes obtained from a Plasmodium in vitro culture.

In a small clinical trial, stored blood samples from confirmed malaria patients, cases of undifferentiated fever, rheumatic-associated disease or heamoglobinpathies, were tested for Plasmodium infection with RDT and MOT test.

The ease with which the system detected a P. M33 Who transmits malaria? But how well do we really know the human infectious reservoirs for Plasmodium falciparum?

It is often assumed that adults, asymptomatic infections and sub-microscopic gametocytes contribute little to transmission.

With the application of molecular gametocyte detection, it is becoming increasingly clear that these assumptions are wrong and therefore malaria control is often based on incomplete information.

I will discuss why current assumptions about human infectious reservoirs are misleading, what this means for malaria control and for the evolutionary trajectories of parasites.

I will outline future studies required to facilitate successful long-term malaria control, which requires an understanding of factors that determine infectiousness and, therefore, identification and monitoring of human infectious reservoirs.

With little knowledge about the infectious reservoirs for Plasmodium falciparum, the selection pressures that interventions pose on malaria parasites will be difficult to estimate and the long-term impact of interventions on disease and transmission will be difficult to predict.

The life history traits of parasites are affected by their environment, which therefore includes the within-host environment.

Parasites also vary in these traits and thus in how they interact with their environment which can be selected for, sometimes inadvertently.

Parasite life-history traits can have important effects on hosts. I will especially consider the life history traits of parasitic nematodes and show the remarkable degree to which these important aspects of parasite biology are intimately linked to host biology.

S35 Sex ratio and morphological polymorphism in an isolated, endemic Teladorsagia circumcincta population Barbara H. Craig, Jill G.

Teladorsagia circumcincta is a polygamous nematode that exhibits morphological polymorphism. Sex ratio is typically female-biased and the male nematodes occur in association with the genetically similar, minor morphotypes T.

In experimental infections, sex ratio and the proportion of minor male morphs observed have been shown to be influenced by both host and nematode related factors.

As similar investigations from natural systems are rare, this study examined whether sex ratio and minor male morph frequency were associated with host age and sex and nematode infra-population size in the isolated Soay sheep population on St.

Generally, the intensity of Teladorsagia nematodes increased with host age until the age of two years before decreasing. In a year when abundance of nematodes was generally higher, nematode sex ratio was negatively associated with host age and tended to be negatively associated with nematode intensity.

Within the male nematode subpopulation T. The presence of each minor morph was primarily associated with the intensity of male T.

Parasitic infections can deplete host energy stores and alter host trade-offs between survival and reproduction.

Understanding the alteration in these host life history traits is essential if the host population dynamics are to be explained.

In this present study, the survivorship and fecundity of adult German cockroaches Blattella germanica was measured in uninfected individuals and cockroaches infected with a protozoan gut parasite, Gregarina blattarum.

Late stage juveniles were removed from colonies and isolated until completion of their final moult.

Newly moulted adults were then paired and monitored for lifetime fecundity and longevity. All nymphs were removed and the cohorts reared until adulthood.

Results show effects on both host survivorship and fecundity under different conditions. Such individual life history trade-offs are likely to have significant effects on host population dynamics, and this will be explored in future work.

In attempting to make sense of the marked diversity in life-histories found among members of each of two ecologically important parasitic insect groups the parasitoid Hymenoptera and the plant-parasitic Lepidoptera , we have sought to identify an organising trait - one that has a pervasive influence, determining and explaining variation in many other life-history variables.

Establishing a connection between the two strategies could provide a unified conceptual framework for understanding the evolution and diversity of life-history strategies in such insects.

S38 Stress, drugs and the evolution of reproductive restraint in malaria parasites Sarah E.

Malaria parasites replicate asexually in their vertebrate hosts, but must reproduce sexually to infect their vectors and transmit to new hosts.

As different parasite stages are required for these functions, the division of resources between these life-history components is a fundamental evolutionary problem.

We test how parasites resolve the trade-off between in-host replication and between-host transmission when exposed to anti-malarial drugs.

We treated multiple drugsensitive and drug-resistant field isolates of the human malaria Plasmodium falciparum with low doses of drugs in vitro.

Previous studies have shown that parasites increase investment in sexual stages when exposed to stressful environmental conditions, such as drugs.

However, we demonstrate the opposite can occur as drug-sensitive parasites facultatively decreased investment in sexual stages in drug-treated cultures.

Furthermore, drug-resistant parasites did not adjust their investment when treated, suggesting that parasites respond to changes in their proliferation rather the presence of drugs.

In contrast to previous studies, we tested parasites from a region where chronic infections contribute significantly to transmission and anti-malarial treatment is common.

We hypothesise that parasite ecology shapes whether in-host survival over between-host transmission are adaptively prioritised when exposed to drug-treatment.

In natural populations, we have found several major-effect polymorphisms controlling resistance to viruses in Drosophila, and at least one of these is matched by polymorphisms that overcome this resistance in viral populations.

These polymorphisms are under strong selection, with resistance sweeping through the fly populations and counter-adaptations sweeping through the virus populations.

We conclude that arms races can drive rapid evolution in both insects and their pathogens. King1, Lynda F.

We found that parasites are locally adapted to the shallow-water margins of lakes where sex is more common and not adapted to deeper habitats where sex is rare.

The results are consistent with the Geographic Mosaic Theory and the Red Queen Hypothesis in that sex is associated with coevolutionary hotspots for virulent parasites.

Most host-parasite systems involve multiple steps of the infection process at which host resistance can evolve.

However, despite the ubiquity of multi-step infection processes, their consequences for host-parasite coevolutionary dynamics have yet to be fully explored; standard coevolutionary models typically assume a single-stage infection process e.

We present a novel coevolutionary model with a two-step infection process which accounts for different gene recognition mechanisms underlying each step of the infection process.

This model predicts unexpected and novel patterns of coevolution. Most significantly, we show that multi-step infection can often lead to unique decoupled coevolutionary cycles, where coevolving parasites and hosts undergo gene frequency fluctuations across different regions of their genomes.

Therefore, attempts to detect co-evolutionary dynamics that focus on functionally coupled genetic systems may fail to detect coevolutionary responses.

Our findings may therefore help to explain puzzling patterns of imbalanced levels of polymorphism in functionally linked host and parasite genes.

Overall, we argue that multistep infection processes are common, resulting in important coevolutionary dynamics not considered by current models.

Accounting for such multistep processes will greatly enhance our understanding of the coevolutionary process occurring within many host-parasite systems.

Whilst the divergence observed at some host resistance and parasite infectivity genes is consistent with this, the long time periods typically required to study coevolution have so far prevented any direct empirical test.

Coevolution also resulted in far greater genetic divergence between replicate populations, which was correlated with the range of hosts that coevolved phage were able to infect.

Consistent with this, the most rapidly 44 evolving phage genes under coevolution were those involved in host infection. These results demonstrate, at both the genomic and phenotypic level, that antagonistic coevolution is a cause of rapid and divergent evolution and is likely to be a major driver of evolutionary change within species.

Theoretical models of the evolution of virulence predict that competition between parasites should select for higher virulence.

While this idea makes intuitive sense, empirical data to support it are rare and equivocal. We investigated the relationship between fitness and virulence during both inter- and intra-specific competition for a fungal parasite of insects, Metarhizium anisopliae.

Contrary to theoretical expectations, competition favoured parasite strains with either a lower or a higher virulence depending on the competitor: when in interspecific competition with an entomopathogenic nematode, Steinernema feltiae, less virulent strains of the fungus were more successful, but when competing against conspecific fungi, more virulent strains were better competitors.

We suggest that in this case the nature of competition direct via toxin production when competing against the nematode, indirect via exploitation of the host when competing against conspecific fungal strains is determining the relationship between virulence and competitive ability.

Meetings Secretary and Hon General Secretary. Lab experiments show that host x parasite genetic interactions have an additional major influence on rates of development, reproduction and survival.

This restricts reproducing parasites to juvenile hosts and to c. Longitudinal studies, based on repeated recaptures of the same host individuals, show that egg output responsible for transmission is maintained in each host age class typically for years before development of immunity that can then protect for over 10 years.

Experimental challenge infection of wild-caught adults confirms effectiveness of this protective immunity. Despite these constraints, the parasite has persisted, dependent on host population recruitment and on the fraction of adult hosts with less effective immunity.

Reece Institutes of Evolution, Immunology and Infection Research, University of Edinburgh, EH9 3JT, UK Both malaria and trypanosome parasites produce specialised stages which are pre-adapted to transmission to the vector and are unable to replicate within the vertebrate host.

These parasites must therefore balance their allocation of resources between within-host replication and betweenhost transmission in order to maximise their fitness.

We have demonstrated that malaria parasites 45 plastically alter their resource allocation strategies in line with changes in genetic diversity of infections and the availability of red blood cell resources, according to the predictions of evolutionary theory.

This includes diverting investment away from between-host transmission when experiencing competition to maximise their ability to compete for host resources.

These findings reveal that an evolutionary-ecology approach, developed to explain the biology of multicellular organisms, can usefully be used to understand the trade-offs parasites face and how, why and when they vary their behaviours.

This allows fine-tuning of existing evolutionary frameworks to formulate predictions for parasite behaviour under certain conditions as well as providing novel tests of the generality of the evolutionary theory.

We describe how this approach has helped us to understand trade-offs in malaria parasites and the next challenge is applying it to other parasites experiencing similar life history trade-offs, such as trypanosomes, to predict their investment strategies for within-host replication and between-host transmission and the resulting implications for virulence.

Fish reduce predation risk and increase foraging success by forming shoals as group members gain benefits shared vigilance, increased mating probability, improved hydrodynamic efficiency compared to solitary individuals.

However, a potential disadvantage of this behaviour is increased parasite transmission. Early work on social organisation within groups focused on interactions between pairs of individuals, but more recently the effects of network interactions and individual variation in behaviour on group structure have been considered.

In the current study, parasitized familiar bold or shy focal guppies Poecilia reticulata , infected with the directly transmitted ectoparasitic worm, Gyrodactylus turnbulli, were introduced into shoals of uninfected bold or shy female conspecifics.

With regard to shoaling behaviour, shy fish formed larger and tighter shoals for longer periods compared to bold fish. Shy-Bold status of infected focal fish also had a significant effect on the average shoal size of both bold and shy conspecifics.

For parasite transmission, results will be discussed in terms of rate and extent of parasite population growth and transfer between shy-bold hosts.

This is the first study to examine the effect of boldnessshyness on transmission of a fish parasite. Alexander D.

Biomass pyramids Lindeman, are a classic concept in ecology that argues that life can be organized into relatively simple trophic levels where trophic biomass is limited by thermodynamic principles that restrict energy transfer across levels.

The pyramidal pattern represents energy flow in communities across all trophic levels, but a glaring omission is parasite biomass. Parasitism is one of the most ubiquitous feeding strategies in nature yet it is unclear how parasites fit into the energetic biomass picture of food web organization.

We investigated 24 food chains with trophically transmitted helminth parasites from a stream ecosystem using empirical measures of weight, as well as estimates of biomass calculated from length and width measures of individual parasites.

Pyramidal biomass patterns emerged in food chains containing the most abundant host species, and these were also the hosts that were infected most frequently.

Differences in pyramidal shape can be partly explained by discrepancies between bio-volume estimates and actual measures of parasite mass.

Nonetheless, it is clear that parasite-host associations seem to fit into biomass patterns that are consistent with thermodynamic principles, which restrict energy flow biomass between trophic levels.

Behnke2 1. School of Biology, University of Nottingham, UK Heligmosomoides is well known as a model GI nematode of laboratory mice, and as a common parasite of woodmice, genus Apodemus, throughout Europe.

The relationship between these two forms is less clear. We have suggested previously that Heligmosomoides from laboratory mice is a distinct species, H.

However, the relationship between these two species was unknown, with a strong possibility that H. It is now clear that H.

Biogeography 33, , but despite the common ancestral host, H. It appears that divergence from H. This represents an excellent system in which to examine the molecular changes accompanying host specialisation following a host shift.

Patterns of coinfection may arise because the hosts themselves are intrinsically or temporarily unusually susceptible to all or to particular parasites; or parasites may interact with one another, either positively or negatively.

However, such patterns, and the processes underlying them, have been investigated only rarely in natural populations, especially so amongst aggregates of different microparasite species.

Here, we elaborate, and seek to account for, patterns of coinfection of cowpox virus, Babesia microti, Anaplasma phagocytophilum and Bartonella spp.

We find that these represent a network of strong associations, both positive and negative. Patterns remain when variations in host susceptibility are accounted for, suggesting that they are mostly generated by interactions between the pathogens themselves rather than by factors associated with exposure risk.

The temporal order of infection can be critical in determining the effect of coinfection on susceptibility, and in general, effects are short-lived, depending on current infection status, rather than previous infections.

Our results highlight the caution that should be exercised when following the standard practice of studying single species of parasite in isolation.

A few hosts become responsible for much of the transmission and the epidemiology is driven by a minority of hosts.

The question is: Why is there so much variation in transmission between hosts? Here, we investigate the role of co-infection in causing such variation.

During the lifetime of any host, they are exposed to a wide diversity of parasites such that at any one time the response to an infection is determined in part by previous infections and in part by their ability to modulate current infections.

This variation may 47 help explain a large component of the variation in infectiousness between hosts. We show strong interactions between the respiratory pathogen Bordetella bronchiseptica and the gut helminth Heligmosomoides polygyrus in mice.

Co-infection increases the number of transmission stages and prolongs the period of shedding in the helminth. Our study demonstrates the fundamental importance of co-infections as one driving factor of variation in transmission between hosts.

Examination of the phylogenetic history of host and bacteria indicate occasional lateral transfer events drive the incidence of Wolbachia.

However, lateral transfer when achieved in the laboratory meets with mixed success; where hosts are distantly related, the infection commonly fails to propagate or show phenotype.

It has recently been discovered that Wolbachia can induce anti-viral resistance in its host. The effects of this resistance on the ability of Wolbachia to propagate is examined in a model exploring the joint population biology of host, Wolbachia and virus.

Natural enemy resistance appears to resolve the Wolbachia paradox, allowing poorly adapted strains to invade which, it is conjectured, then evolve improved transmission and phenotype in their new host species.

S52 Do worms promote or prevent malaria? Using meta-analysis to assess the evidence in mice and men Sarah C. The question of whether coinfecting helminths and malaria parasites interact has attracted much attention in recent years, and is important in the context of intervention strategies for diseases caused by both types of parasite.

The literature now contains numerous empirical studies investigating whether worms affect malarial disease, both in human populations and also in murine lab models, yet firm conclusions have yet to emerge.

Here we report the results of two parallel meta-analyses covering the human and mouse literature respectively in which we quantitatively assess existing evidence on this question.

Specifically, we address 1 whether studies suggest antagonistic or synergistic effects of helminth infection on malarial disease and 2 which factors explain variation in effect size among studies, including biological factors such as host age, helminth species, and the outcome measure used, as well as methodological factors such as experimental design.

Via Celoria 10 Italy. Analysis of the determinants of parasite community structure is a key topic in parasite ecology, with a growing focus on the influence of interaction between co-occurring species.

However, communities are allocated, mainly through qualitative assessment, to one or other of 48 these two extremes, thereby missing the continuum that occurs in nature.

Analysis at a population level may miss the role of intrinsic and extrinsic factors which lead to these differences.

We developed a measure of within host contact for each individual parasite and apply this measure to mountain ruminant parasite communities, which are characterized by high seasonal, age and sexual variability.

Mean parasite interaction showed high variability mainly related to temporal effects, with a lesser influence played by host factors.

The largest surviving marsupial carnivore, the Tasmanian devil, Sarcophilus harrisii, is threatened with extinction by a cancer in which the tumour cells themselves are the infectious agent.

The tumour can be considered a clonally reproducing parasitic mammalian cell line. Analysis of extensive field data shows that transmission is frequency, rather than density dependent, which means that this species-specific parasite is capable of causing the extinction of its host.

Management actions being investigated include isolating uninfected animals, disease suppression by removal of all animals showing clinical signs, and attempting to identify genotypes that may show some resistance.

A disease suppression trial on a semi-isolated peninsula has so far failed to halt population decline or to show any decrease in the rate of transition from healthy to infected status.

Tumour cells from one animal are thought to be able to infect another because of very low MHC diversity in the devil population.

However, the disease is now spreading to the north-west of Tasmania where MHC diversity is higher. Prevalence is increasing more slowly in this area than in previously infected locations and age structure remains similar to uninfected populations.

Whether this indicates that some of the north-western genotypes are resistant remains unclear and the outcome of coevolutionary forces on the host parasite interaction is also uncertain.

The ecological circumstances influence, for example, the abundance and virulence of parasites. Moreover, different ecological circumstances may set different costs and thus shape different trade-offs and life-history strategies.

Pied Ficedula hypoleuca and collared flycatchers F. They breed in different parts of Europe, but their distributions overlap in two contact zones.

They experience seasonal changes in both relative fitness and in malaria infection patterns. To investigate whether malaria infected and non-infected 49 birds had occupied different areas on their wintering grounds in Africa, we determined the prevalence and types of malaria blood parasites using a PCR protocol.

Such signatures reflect individual's diet and environmental conditions at the wintering location during feather replacement. I compare these results with breeding performance data and discuss possible consequences for host species.

It produces a distinctive pathology, consisting of white masses of spores visible in the abdomen of the host, which is commonly used as the diagnostic feature when identifying the infection.

Difficulty in obtaining molecular data has resulted in the species only previously being characterised ultrastructurally. Phylogenetic analysis by Bayesian Inference suggests that the species is actually a member of the genus Dictyocoela.

A formal description of Dictyocoela has yet to be published. However, previous studies associate Dictyocoela duebenum with light infections of the gonad and ectodermal tissues, with no mention of the gross muscle pathology associated with T.

Therefore to obtain a true full description, infection in the musculature must also be investigated. It is possible that if Thelohania muelleri is in fact a Dictyocoela parasite that other morphologically similar species such as T.

Otter Lutra lutra populations in the UK have greatly recovered following a severe decline during the s, however further investigation of their parasitic fauna is important and may help prevent future population crashes.

As road-killed otters from England and Wales are routinely collected for post mortem by the Cardiff University Otter Project, gall bladders were screened for parasites.

Two digenean species were recovered from the bile and bile ducts, Pseudamphistomum truncatum and Metorchis albidus. Both species are thought to have only recently been introduced to the UK and there is no record for either prior to At present, there is no detectable increase in prevalence with year for either parasite.

The pathological damage these parasites cause to the biliary system makes it necessary to monitor their distribution to protect both wild and domestic piscivores against these generalist pathogens.

The presence of these parasites in the UK now provides an ideal opportunity to understand how a pathogen can spread across a novel habitat.

Alison M. Dunn, Jaimie T. Dick, Michael Armstrong, Hazel C. Clarke, Keith D. Farnsworth, Melanie J. Here, we investigate the influence of parasitism on the predatory interactions between native and invasive species in two ongoing UK invasions.

Gammarus pulex is an invasive amphipod that competes with and excludes the native G. Surprisingly, we found that G.

The animals displayed Type II functional responses FRs , with the FR for parasitized animals rising more steeply and with a higher asymptote compared with unparasitised individuals.

The increase in the predatory response of infected hosts may enhance the impact of this invader on the recipient community.

Parasitism may also increase the impact of invasion by the American signal crayfish, which is driving the native white clawed crayfish extinct throughout Britain.

Native crayfish infected by the microsporidian parasite Thelohania contejeani showed a lower FR than did uninfected native or invasive species as well as a change in diet.

These changes reduce the ability of the white clawed crayfish to compete with the invasive signal crayfish and may increase the rate of extinction.

Dengue virus, the causative agent of dengue fever and dengue hemorrhagic fever, is widespread throughout tropical and subtropical regions.

The virus exists as four distinct serotypes, all of which have co-circulated in Bangkok for several decades with epidemic outbreaks occurring every years.

Using an epidemic model with stochastic seasonal forcing showing year epidemic oscillations, we demonstrate that moderate cross-protective immunity gives rise to persistent outof-phase oscillations similar to those observed in the data, but that strong or weak cross-protection or cross-enhancement only produces in-phase patterns.

In many regions dengue incidence fluctuates seasonally with few if any infections reported in unfavourable periods. It has been hypothesized that vertical transmission within the mosquito population allows the virus to persist at these times.

Using a mathematical model we argue that at these infection rates vertical transmission is not an important factor for long term virus persistence.

These approaches achieve different levels of impact on the diseases they are aimed against, depending on host-parasite ecologies for each of disease.

In the case of indirectly transmitted infections, such as lymphatic filariasis and schistosomiasis, these ecologies can be complicated, involving the infection dynamics of several life-stages of the parasite within different hosts.

We investigate the consequences of parasite population dynamics on the control helminth infections. We construct mathematical models of the relevant worm population ecologies, and investigate the effects of density dependent mechanisms on 1 the threshold vector biting rate, 51 below which infection cannot be sustained; 2 the breakpoint parasite density, which implies the existence of a minimum parasite population below which extinction will result; 3 the rate at which the parasite level will change when it is perturbed from its initial level.

Fitting the models to available human and, in some cases, vector data - while quantifying residual uncertainty in the models - shows that parameters relating to the density dependences vary over geographical areas and that these parameters influence estimates of parameters such as R0.

We extract general principles from these results to highlight the importance of considering complex systems dynamics in the design of effective helminth control and elimination programs.

Malaria is a complex vector-borne disease and a major public health burden in endemic regions around the tropic.

Non-endemic regions have shown pronounced patterns of increase in incidence and re-emergence in the past three decades. Despite extensive knowledge accumulated for almost a century on the biology of both the parasite and the mosquito vector, the reasons for these patterns of exacerbation are not well understood.

Climate change, human migrations, and drug resistance are different hypotheses but evaluating these mechanisms from time series data remains elusive.

In this work, we focus on the recent past and on the temporal population dynamics of the disease, to address whether warmer temperatures have already increased the incidence of epidemic malaria in an East African highland.

Our analyzes rely on a monthly time series of confirmed cases from to in the Kericho region of Kenya and on an epidemiological model for the population dynamics of the disease that includes both the human host and the mosquito vector.

Our findings suggest that climate change has already played a role in the exacerbation of malaria in this region. The relative effect of other potential factors acting either in addition to or synergistically to warmer temperatures remains to be carefully evaluated.

Department of Biology and 4. Departments of Biology and Entomology, Pennsylvania State University, University Park PA , USA Understanding interactions between parasites, host resources and other within-host 'ecological' factors is important because they ultimately shape disease outcomes of interest e.

Malaria parasites are known to differ in how they use host resources, for example the four human Plasmodium species invade different age ranges of host red blood cells RBCs.

Such differences in host exploitation traits give rise to different levels of disease severity and are predicted to determine the outcome of competitive interactions between species and strains.

Using a model malaria system P. We find some support for our model predictions, and discover that within-host ecology matters, suggesting that malaria parasites adaptively vary their host exploitation strategies in an adaptive way in response to changes in the within-host environment.

Little1, Karen S. Wagner2, Edoh S. The parasite Onchocerca volvulus has, until recently, been regarded as the cause of a chronic yet non-fatal condition.

New analyses, however, have indicated that in addition to blindness, the parasite can also be directly associated with human mortality.

Such analyses also suggested that the relationship between microfilarial load and excess mortality might be density dependent.

Determining the functional form of such relationship would contribute to quantify the population impact of mass microfilaricidal treatment.

The goodness-of-fit of three candidate functional forms were explored and a saturating exponential type function was deemed to be statistically the best fit.

These conditions will certainly change epidemiological parameters, but could also alter selection on parasite life history traits.

The most obvious difference between hosts living under natural conditions, as compared to farmed hosts, is a significant increase in population density.

It has been shown that host population density is positively correlated with both parasite abundance and species richness.

Moreover, in situations where parasites experience a rapid increase in the number of available hosts, transmission opportunities will be changed, which in turn could select for new combinations of parasite life history traits.

This is of particular concern, since life history traits of parasites could be linked to virulence.

The global rapid increase in fish farming during the last decades could be considered a largescaled experiment providing an opportunity to study the effects of artificially increased host density on parasite epidemiology and evolution.

Using salmon farming as an example, this talk will review the emergence of parasites and pathogens following a dramatic ecological change in the marine environment, and also discuss possible evolutionary implications.

This project represents a considerable challenge to groups focusing on neglected tropical parasitic diseases like onchocerciasis.

Aside from the perceived unsuitability of the DALY to measuring the burden of chronic parasitic infections of the poor, many disease cases go unreported due to unsatisfactory monitoring and registration of morbidity within these populations.

We have updated the disease model to include morbidities associated with onchocercal infection not included in previous estimates.

Non-linear relationships between parasitological indicators and various morbidities e. It is thought to present the second largest health burden of any disease worldwide.

Accurate modelling of geographic distribution of the disease at a region level is crucial to guiding the planning of control programmes.

We attempt to map the prevalence of LF infection across Africa using a Bayesian generalised spatial linear model in conjunction with community-level infection data obtained from the published literature.

The model parameters are estimated using Markov chain Monte Carlo techniques. We use the model to explore 1 , the relationship between LF infection prevalence and the environmental variables, 2 assess the biologically plausibility of the estimated functional relationships, and 3 relate this to climate dependency in LF transmission dynamics.

The prevalence map is also used to estimate the total number of people infected with LF in Africa.

Finally, we use future climate predictions to investigate the impact global warming could have on future LF spatial distribution, prevalence and burden.

Hayward, Alastair J. Wilson, Jill G. Pilkington, Josephine M. Despite increasing evidence for a decline in immune performance with advancing age in natural populations, it remains unclear how this translates to changes in actual parasite burdens.

Moreover, in populations where individuals may experience heterogeneous and even adverse environmental conditions, there is the potential for large variation in individual life-history trajectories.

We present analysis of gastrointestinal helminth faecal egg count FEC data collected over 20 years from a free-living population of Soay sheep, with the aim of investigating the impact of ageing and environmental conditions on parasite resistance.

Finally, we show that these factors interact, such that individuals that have experienced adverse and stressful conditions show an accelerated age-specific increase in FEC when compared to individuals that have experienced favourable conditions.

Chronological age is thus associated with a decline in parasite resistance, but heterogeneity in experience of 54 environmental conditions and stressors seems an important source of variation in changes in parasite resistance across the host life-history.

S68 Effects of temporal environmental variation on host-parasite dynamics in the Paramecium caudatum - Holospora undulata system Alison B.

It is important to understand how such variation affects epidemiological dynamics in host-parasite systems. We explored effects of temporal variation in temperature on experimental populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata.

Infected and uninfected populations of 2 P. Variable conditions caused greater declines in host populations at higher temperatures.

This effect was disproportionate for host clone VEN, especially for infected populations. Variable conditions were also detrimental for the parasite causing greater declines in levels of infection.

These results highlight how variable conditions can impact persistence of both host and parasite populations. They also demonstrate that sign and rates of population decline can depend on host genotype and parasite infection.

A, 7eme Etage, CC 7 quai St. Extensions of this approach are necessary to understand the potential for interaction between different parasite strains within the same host: often they will feel each other's presence only via their effect of the immune system.

The approach also has highlighted the importance of a few neglected questions: modellers typically make the assumption that infections are chronic or acute depending on the disease they want to model but this aspect should actually be an outcome predicted by theory.

In particular, embedded models tend to predict chronic infections: the mechanisms that permit an immune system to eradicate an infection are poorly understood.

Many embedded models are inspired by models for predator-prey interactions but it is worthwhile to point out that models for parasite-immune system interactions be interesting for ecologists.

Long , Alexia T. Karanikas, Eric T. Harvill, Andrew F. Despite over fifty years of population-wide vaccination, whooping cough is re-emerging in highly vaccinated populations.

Although Bordetella pertussis is regarded as the major causative agent of human whooping cough, B. The widely-used acellular whooping cough vaccines aP are composed exclusively of B.

Using a rodent model of infection, we show that aP vaccination helped to clear B. We show that such vaccine-mediated facilitation of B.

Rather, aP vaccination, by reducing lung inflammatory responses measured by cytokine responsiveness in the lung and lung neutrophil recruitment, delayed B.

Our data raise the possibility that aP vaccination can create hosts that are more susceptible to B. Karen J. Fairlie-Clarke, Tracey J.

To determine the relative strength of cross-reactive versus antigen-specific responses, in co-infected mice, we used ELISA to calculate antibody titre from a serial dilution of serum.

We further examined whether cross-reactive responses were targeted toward carbohydrate or protein moieties by treating the parasite antigens with periodate, thus disrupting carbohydrate epitopes by oxidising carbohydrates to aldehydes.

Periodate treatment affected both antigen-specific and cross-reactive responses. For example, if the antigenic distance between two parasites is small the immune system may not perceive them as different and crossreactivity would result.

Maintaining some degree of polyclonality may confer a broader spectrum of protection raising the interesting question of whether production of cross-reactive antibodies might be the optimal response for a host faced with infection by an unpredictable range of parasites.

Here we demonstrate the application of such an approach to generate meaningful immunological profiles for wild mammals.

We sampled a field vole population across a full annual cycle and developed a battery of cellular assays in which functionally different pro- and anti-inflammatory signalling responses transcription factor and cytokine mRNAs were activated and quantified by Q-PCR.

Temporal trends and infection status accounted for a significant proportion of the observed variation in immunological expression. There were highly significant annual and non-annual temporal immunological trends and systematic differences in the immunological status of animals occurred between equivalent points in the annual cycle Winter and Pinpointing the causes and consequences of such non-seasonal temporal variability may help identify underlying environmental drivers of individual fitness and demographic fluctuation.

However, the majority of such studies focus on wellnourished individuals that are under limited environmental stresses, often infected with only a single experimental pathogen at a time, and are therefore not ecologically valid.

The relatively few studies that have concentrated on natural populations have largely focussed solely on the genetics of the major histocompatibility complex; there is therefore a need to expand research away from the MHC to other immune genes and away from laboratory to natural populations.

Our work has addressed both of these issues by examining the genetic diversity of cytokine genes, key regulators of the immune response, within a well-studied natural population of field voles Microtus agrestis in Kielder Forest, UK.

We used population genetic methods to identify a signature of natural selection acting on several of these genes and then demonstrated that this genetic diversity can lead to phenotypic effects, such as variation in gene expression levels and parasite resistance between individuals.

We conclude that immunogenetic diversity in the vole population is widespread and that host-parasite interactions provide a possible mechanism for its maintenance.

Hanna1, G. Brennan2, D. Sammin3, S. McConnell1, F. Forster1, H. Edgar1, D. Moffett1, M. McConville2, E. Certain well-defined histological changes are recognisable in the reproductive structures of TCBZsensitive flukes following recent TCBZ treatment of the host.

Hence histopathological methods can be used to investigate TCBZ resistance status in field cases of fasciolosis. Amongst the changes seen in TCBZ-sensitive flukes exposed to metabolites of TCBZ in treated sheep, the development of apoptotic-like bodies in testes, vitelline follicles and ovary predominates.

The cells mainly affected are those undergoing mitosis or meiosis. The occurrence of apoptosis in this situation has been verified by the use of a commercially available kit for immunocytochemical localization of apoptotic cell death.

The method, which relies on recognition of DNA cleavage fragments generated by endonuclease following a trigger event, could improve sensitivity and facilitate quantification of histopathological analysis in the investigation of TCBZ resistance.

Schistosoma haematobium and Schistosoma bovis are blood trematodes that cause diseases in human and ruminant hosts, respectively.

Echinostoma caproni is an intestinal trematode that mainly affects mammals and birds and is used as a model to study helminthiasis. Sera from S.

Our results show that there is differential protein expression between the three species. Furthremore we demonstrated that as expected, the antigen recognition profiles differed between sera from animals infected with S.

Interestingly, we also demostrated that there were some commonly recognised antigens. The relevance of our findings of both differentially expressed proteins and common antigens are discussed in relation to phylogenetic studies, diagnostic tests and vaccine development.

During chronic infection, humans are exposed to several different schistosome lifecycle stages. One hypothesis for the slow development of protective immunity is that exposure to dying longlived adult worms is needed to stimulate a protective response.

Another hypothesis is that a threshold level of antigen must be experienced before a protective response is initiated. Mathematical models were used to investigate the importance of different parasite lifecycle stages in stimulating antibody responses, and to assess the impact of an antigen threshold.

Model outputs were compared with Schistosoma haematobium field data from Zimbabwe. Results from deterministic models describing mean levels of infection and antibody in homogeneously exposed populations indicated that protective antibody responses stimulated by dying adult worms can reproduce age-infection and age-antibody profiles consistent with field data, but that other lifestages could also be the principal source of protective antigen.

Stochastic individual-based models, which permit heterogeneous exposure, allow us to determine whether these mechanisms can additionally explain observed infection and antibody distributions.

Identifying the mechanisms underlying the development of protective immunity is important for understanding how mass chemotherapy programmes may impact the development of natural immunity, with consequent effects on infection.

Data from experimental models suggest that immunity is also influenced by regulatory T cells Treg , but as yet studies on Treg in human schistosome infections are limited.

We therefore characterized regulatory and 58 activated T cell Tact populations in Zimbabweans aged years exposed to Schistosoma haematobium parasites.

Moreover, there was a significant positive correlation between Treg:Tact ratio and infection intensity. The strongest correlation occurred in the youngest age groups in whom infection was rising and peaking, but the association was lost in the older age group with declining infection levels.

We here describe a completely different mechanism of immune modulation where host lipoproteins serve as transporters of schistosome antigens.

Like many schistosome proteins, these antigens are glycosylated with schistosome specific glycoproteins. As a result of transfer of schistosome antigens to host lipoproteins, circulating antibodies against schistosome antigens will indirectly bind to these lipoproteins.

We have demonstrated the presence of IgG on low-density lipoprotein particles from serum from infected individuals, whereas no antibodies were found on lipoproteins of healthy controls.

Subsequently, these antibody-opsonised lipoproteins are phagocytosed by immune cells carrying an Fc-receptor.

Indeed, accumulation of lipids within several types of blood derived immune cells occurred in infected individuals only.

In vitro, this lipid accumulation was associated with apoptosis and reduced viability of neutrophils. The consequences of these lipoprotein binding antibodies for immune cells and for the anti-helminth host response will be discussed.

S79 Eosinophil degranulation against adult Onchocerca ochengi during macrofilaricidal chemotherapy is dependent on depletion of Wolbachia Rowena D.

Hansen1, Germanus S. Bah2, Udo Hetzel1, Vincent N. Tanya2, Alexander J. The basis of the symbiotic relationship between filariae and their Wolbachia endosymbionts is thought to be metabolic, but a role for Wolbachia in defence against immune attack has received little attention.

Neutrophils are attracted to Wolbachia but they are replaced by eosinophils following antibiotic chemotherapy, which degranulate on the worm cuticle.

However, it is not clear whether the eosinophils are involved in killing the filariae or if they are attracted secondarily to dying worms.

In this study, cattle infected with O. In contrast to oxytetracycline, melarsomine had no significant effect on the viability of Wolbachia.

Eosinophil infiltration and degranulation increased significantly only in the oxytetracycline group; whereas nodular gene expression of the chemokine interleukin-8 was lowest in this group.

Moreover, in the early time-points, intense eosinophil degranulation was associated with worm vitality, not degeneration.

These data are consistent with a role for eosinophils in antibiotic-mediated killing, and suggest that Wolbachia prevents a local eosinophilia by recruiting neutrophils.

This shapes the way we think about age profiles of infection, distributions of parasites among hosts, and mechanisms regulating parasite populations.

Many large-scale chemotherapy-based programmes are now in place which aim at controlling infection, reducing morbidity, and eliminating infection where deemed possible.

Depending on whether anthelmintics are mass administered or targeted at particular age- or occupational groups, age-infection profiles will be modified; immune responses will be affected; prevalence vs.

Additionally, we need to monitor for changes in drug efficacy and develop novel assays for detection of active infection and exposure as the sensitivity of parasitological indicators decreases, programmes approach transmission breakpoints, and tools are required to ascertain when to stop.

We need to understand how the parasite population biology paradigm is changing if we aim at supporting parasite control efforts effectively.

S81 Porcine parasites in Northern Ireland: incidence, distribution and correlation with management and control strategies J.

Black1, J. Marks1, A. Endoparasitic worms inflict a huge economic burden on pig production through reduced growth, poor feed conversion efficiencies and higher medication costs.

As yet, anthelmintic resistance has not been reported in swine herds in the UK or Ireland. However, benzimidazole and levamisole resistant nematodes have been identified from herds in Germany concurring with the situation in other nematode parasites of sheep and cattle where multi-drug resistance is rife.

The aim of this study is to investigate the prevalence and distribution of helminth parasites in pig units across Northern Ireland N.

Other species identified included: Hyostrongylus rubidis, Oesophagostumum dentatum, Metastrongylus apri, Trichuris suis and Fasciola hepatica.

These findings indicate that despite good husbandry practice, high-levels of worms are commonplace on most pig units in N. Echinococcus granulosus is a dog tapeworm that causes the zoonotic disease, cystic echinococcosis.

Canine echinococcosis appears to have re-emerged in Powys, Wales following a control programme in the s Buishi et al. The Office of the Chief Veterinary Officer and 60 the Department for Public Health and Health Professions in the Welsh Assembly Government jointly funded a pilot dog worming campaign as a preventative public health measure.

To evaluate the impact and efficiency of a short-term supervised dog dosing scheme, collection of faecal samples on farm visits and worming of dogs with praziquantel commenced in South Powys in May In Year 1, approximately canid faecal samples were collected from registered farms and delivered to the University of Salford to be tested.

In total faecal samples were tested by coproELISA, of these samples were collected at baseline and were found to have a coproantigen prevalence of A total of samples tested after 3 treatments gave a coproantigen prevalence of 0.

The study will continue to compare the coproantigen prevalence over one year after cessation of dosing.

Nicotinic acetylcholine receptors nAChRs are significant drug targets for parasitic nematodes, and several sub-types of these receptors are present on body wall muscle.

We recently identified a novel nAChR subunit gene, acr, from Ascaris suum. A survey of parasitic nematodes, using a combination of sequence data and primary material, demonstrates that acr is conserved in several parasitic species from clades III and V, including Brugia malayi, Haemonchus contortus and Dirofilaria immitis.

To date however, no evidence has been found of acr in any free-living or plant parasitic nematode.

A specific antibody against the Asu-ACR subunit was produced; immunocytochemistry on native tissue showed that the subunit was expressed in the head muscle of A.

Sequence similarities with other nAChRs and computer modelling predicted that ACR was capable of forming a homomeric channel.

To assess the impact of allelic diversity on naturally-acquired immunity, we: a sequenced the ectodomain of P. Seventy-eight unique haplotypes were identified from alleles.

No clustering of allelic types with disease severity was observed, but allele frequency distributions were indicative of balancing selection.

Antibodies to three allelic AMA1 proteins were highly correlated, and associated with protection from clinical malaria. Despite the extensive antigenic diversity, antibodies to conserved epitopes in AMA1 may be sufficient to contribute to clinical protection.

Theander, Morten A. Centre for Medical Parasitology at Department of International Health, University of Copenhagen, Copenhagen University Hospital Rigshospitalet Pregnancy-associated malaria PAM is a major cause of maternal anemia, stillbirth and delivery of low-birth-weight children in malaria endemic areas.

The disease is caused by accumulation of P. Although the direct correlation to in vivo protection is unclear the inhibition rate suggests that the DBL4-VAR2CSA antigen could be used in a vaccine formulation with any of the tested adjuvants.

To further understand what a tailored protective immune response against PAM should aim for, the resulting antibodies from these immunizations were analysed regarding titre, specificity, epitopes bias and affinity.

Reece Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK Despite the partial protection against malaria observed for young infants, the evolutionary and ecological consequences of maternally transferred antibodies remains poorly understood.

Vaccine development has revealed the importance of antigenic variation and genetic diversity for immune protection but the impact of this diversity for maternally transferred protection is yet to be tested.

We used the rodent malaria model Plasmodium chabaudi, to test whether maternally transferred immunity is: a strain specific; b influenced by drug treatment of mothers; and c differs according to genetics of hosts and parasites.

To do so, we compared infection dynamics and virulence experienced by pups of three different mouse strains during homologous challenged with the same strain as their mothers or heterologous infections.

We observed a higher mortality for pups from non infected mothers or mother infected and drug treated i. We also observed strain specificity of maternally transferred protection as the protective effect of maternal antibodies was stronger during homologous infections.

Our results open perspectives for a better understanding of the evolution and ecology of maternally transferred immunity but also to determine how maternal drug treatment might affect the protection conferred to young children.

It detailed early successes and promise of an 32 extract, qinghaosu. This talk will discuss the history and impact of this paper and the development of artemisinin and artemisinin-based combination therapy ACT.

The pandemic, the first since the discovery of the transmission mechanism of malaria, found the country's physicians already mobilised against the disease.

Nonetheless it is estimated to have affected one third of the population. A stream of publications and nation-wide surveys that range between and and the descriptive data they provide set the pandemic outbreak in the context of the country's fragmented geography and its history of endemic malaria.

Doctors are having to resort to Orodar sulfadoxine-pyrimethamine , an old-line malaria drug that is useless against many strains of the parasite.

Kodjo Edoh, the head of the Medicins Sans Frontieres mission in Madi Opei, a former rebel stronghold, investigated the shortages of ACTs in public hospitals and found that officials were stealing the medications and selling them on the black market.

With the help of Interpol, the Ugandan government is now cracking down on thefts and prosecuting corrupt officials.

But with parasite resistance to artemisinin - the key component of ACTs - now being reported in Cambodia, and a growing worldwide trade in counterfeit malaria medications, time is running out.

Is this a new problem or history repeating itself? Instead it will explore how a series of dispersed and dissimilar debilities came to be represented as a single, continuous epidemic of malaria in Bengal and beyond.

Such a detailed understanding of how parasites and hosts interact at the molecular and population levels would clearly be of enormous benefit, not just in advancing basic biological knowledge, but also in the practical development of more effective vaccines and therapies.

But how realistic are these expectations? And is there a danger that we seriously underestimate the complexity, diversity and unpredictability of the systems we are studying?

We have already shown how proteomics can be used alongside other functional genomic tools to help understand fundamental mechanisms of host-cell invasion and the modification of host-cell function to sustain successful parasitism.

However, despite the huge progress that has been made toward describing the proteomes and sub-proteomes of some parasites, extending these studies beyond the merely descriptive raises considerable technological difficulties.

A major challenge is that of exploiting the next generation of quantitative proteomic technologies to help model the key relationship between mRNA transcription and protein expression in parasites.

I will discuss how the recent history of mankind has altered the evolutionary trajectory of T. The mouse possesses a powerful cell-autonomous resistance system against T.

Winpenny, Paul R. Giardia lamblia, an important cause of diarrheal disease, resides in the small intestinal lumen in close apposition to epithelial cells.

Since the disease mechanisms underlying giardiasis are poorly understood, elucidating the specific interactions of the parasite with the host epithelium is likely to provide clues to understanding the pathogenesis.

We have used the Ussing chamber system to investigate the effect of both giardia co-cultures and giardia supernatants on ion transport in monolayers of the human colonic epithelial cell line, CaCo-2, grown on permeable supports.

There 34 was a reduction in both the forskolin-stimulated, GlyH inhibitable short circuit current Isc and the uridine 5'-triphosphate UTP -stimulated Isc from CaCo-2 monolayers co-cultured with giardia.

No difference was observed between different giardia isolates. Importantly however, in all cases transepithelial electrical resistance TEER of the CaCo-2 monolayers decreased after 24h of coculture with the parasite suggestive of a disruption to the epithelial monolayer.

Addition of giardia culture supernatants alone to the apical side of the CaCo-2 monolayers resulted in a reduction in the forskolin-stimulated, GlyH inhibitable Isc.

This study raises the possibility of the presence of a soluble mediator whose activity abrogates CaCo-2 epithelial cell function. This disruption might contribute to gastrointestinal symptoms in infections involving Giardia strains which do not express well-established enterotoxins.

Two species of Cryptosporidium, C. Genome representatives of C. Using comparative genomic tools, we identified over putatively specific genes, the majority corresponding to hypothetical proteins.

In order to investigate this apparent specificity, we used PCR to amplify twelve of these genes in a panel of UK clinical isolates, previously genotyped at the Cryptosporidium Reference Unit.

As the amount of DNA available for testing was limited, we used and validated whole genome amplification WGA for archiving of these isolates.

While the majority of the tested genes were present in both species, sequence analysis provided a uniquely unbiased selection of coding sequences for multilocus analysis and allowed discovery of a wide variety of novel SNPs, thus enabling more robust genotypic analysis.

Interestingly, our secondary screen eliminated all but 2 of the putative species specific genes. The biological function of these genes Cop-1 and Chos-1 is currently under investigation, in addition to their potential as species determinant, epidemiologic and diagnostic marker.

Here, we present data on the identification, protein features and evolutionary relationships of identified VAL homologs within the phylum Platyhelminthes.

Using new sequencing data combined with existing genomic and transcriptomic data, novel VAL homologs were discovered in over 20 platyhelminth species.

Phylogenetic and protein feature analyses highlight the existence of both group 1 and group 2 members in all four major platyhelminth classes Trematoda, Monogenea, Cestoda and Turbellaria.

Farias1, Iain W. Hoffmann2 1. Here, distinct expression patterns were observed, with many of the SmVALs being stage-specific and some displaying constitutive patterns of expression.

Mapping the transcript profiles to SmVAL phylogeny provided an insight into their evolution and their putative function within the parasite.

Together, our results are discussed in light of the anticipated need for alternative strategies to combat schistosomiasis. Taylor, Neill Storrar, Judith E.

Consequently, the efficiency of a vaccine against filariasis will depend on how well it circumvents filaria-driven immunosuppression.

We developed a vaccine strategy that specifically targets filarial excretory products involved in immunosuppression, while enhancing antigen processing and type-2 adaptive immune responses.

The L. In order to enhance antigen processing of the target protein by the host, we fused the target with an anti-DEC antibody fragment.

Mice immunised with mutated forms of parasite proteins produced more specific antibody post-challenge and showed strongly increased lymphocyte stimulation above controls.

In conclusion, we have designed vaccines that circumvent parasite-induced immunosuppression, enhance antigen-processing and skew the immune response towards a protective phenotype.

Additional benefits of this strategy are that the effects of these vaccines are long-lived, and costeffective. Previous work has shown that the gene encoding the enzyme GTP-Cyclohydrolase GTP-CH is much more highly expressed in the 3rd free-living, L3 stage of the nematode Teladorsagia circumcincta compared to the 4th parasitic, L4 stage.

This observation has also been made in several other Clade V nematode species. As the rate limiting enzyme in the production of tetrahydrobiopterin, there are a number of different pathways which could require such high levels of GTP-CH.

A number of different products are generated by these pathways, including dopamine, serotonin and melanin. To examine which products and pathways are critical for L3 stage worms, investigations have been undertaken in T.

Analysis of gene expression in D. Analysis using hypobiotic and non-hypobiotic larvae showed that GTP-CH gene expression was similar in both, implying that the enzyme is not directly involved in the larval arrest of D.

S24 Genetic changes associated with the selection of an ivermectin-resistant isolate of Haemonchus contortus. Ivermectin resistance has become a serious concern in veterinary parasitology, yet the genetic basis of this resistance has yet to be determined, though changes in both the P-glycoproteins and ligand-gated chloride channels have been reported.

Part of the reason for this is the high level of genetic diversity seen between parasite isolates. In an attempt to overcome this, we selected a new ivermectin-resistant isolate of H.

Worms fully resistant to the normal therapeutic dose of ivermectin 0. The ivermectinresistant population was also resistant to thiabendazole in the egg-hatch test and possessed an increased level of benzimidazole resistance-associated alleles We are examining the sequences of mRNAs encoding ligand-gated chloride channel subunits sensitive to ivermectin.

We have identified several genes homologous to Pglycoprotein in the H. These data will identify candidate ivermectin resistance-associated genes in this parasite.

Here we use bivariate variance components analysis to investigate the relative roles of host genetics, shared household environment and known risk factors in determining predisposition to hookworm and Ascaris infection.

Infection intensity faecal egg counts , pedigree information and socio-economic and remote-sensed environmental risk factors were measured in 37 a treatment-reinfection study of people in Brazil.

Results showed significant predisposition to hookworm and Ascaris infection. The heritabilities of hookworm and Ascaris infection intensity were 0.

There was a high positive genetic correlation between pretreatment and reinfection Ascaris intensity, suggesting that host genetics accounted for the majority of the observed predisposition to Ascaris.

However, the genetic correlation for hookworm infection was lower, with household and environmental factors playing a larger role in predisposition to hookworm infection.

The lecture will discuss how changes in the world we live in over the past few decades have influenced the pattern of the emergence and spread of infectious agents.

Increased mobility, changing demography and increased urbanisation - and also scientific advances that enable new pathogens to be indentified and tracked - will be examined.

Growth in human population size and the increase in megacities with over 10 million inhabitants, promotes both the transmission and evolution of infectious agents.

How these spread around the world is very much influenced by air traffic flow between the world's major cities. Novel ways of examining the distribution of human population density and interactions within and between centres of high and low population density will be discussed.

These include satellite sensing, simulation methods, digital communication and pathogen genome sequencing. The talk will use examples of recent epidemics including H1N1, SARS and HIV-1 to illustrate how our changing patterns of habitation, travel and interaction have influenced pathogen evolution and spread.

Mark C. Field Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QT Intracellular transport is the process by which macromolecules are delivered to the organelles constituting the endomembrane system and also provide mechanisms for secretion to the environment, for uptake of nutrients and control of signaling pathways.

In protozoan parasites this process is vital as the cell surface represents the host-parasite interface with the host immune system.

In African trypanosomes immunoglobulins and other immune effectors recognizing or bind ing the parasite surface are removed by efficient endocytosis, proteolysis and recycling, maintaining the variant surface glycoprotein density at the plasma membrane.

Ensuring a constant surface protein composition is also vital to additional cellular functions. Our contributions towards understanding mechanisms of selective surface protein turnover will be discussed.

More recently, parallels between membrane transport and distinct systems involved in membrane deformation have emerged.

Specifically, strong similarities in the structures and architectures of vesicular transport factors and the nuclear pore complex have emerged.

These findings have allowed the development of a holistic paradigm for the evolution of membrane transport, and an emerging model for the origins of these systems back to the last eukaryotic common ancestor and beyond.

Specific examples exploiting broad genome sequence information, proteomics and functional studies focused on African trypanosomes will be presented, in the context of reconstructing the order in which the organelles of the endomembrane system arose and furthering understanding of trypanosome cell biology.

Throughout this process, especially during ookinete traversal of the mosquito midgut epithelium, the mosquito immune system kills the vast majority of parasites.

Intestinal epithelial immunity forms the first line of defence against Plasmodium, followed by a second line of humoral defence in the mosquito hemolymph.

The first line is controlled by an NF-[kappa]B signalling pathway mostly triggered by symbiotic bacteria that reside in the mosquito gut and drastically proliferate soon after a female mosquito bloodmeal.

The second line consists of a constitutive machinery of hemolymph proteins, equivalent to vertebrate complement. Its activation leads to a dramatic reduction of parasite numbers or complete control of the infection and transmission blockade.

M27 Genetic control of mosquito populations to combat malaria: modelling approach A. Deredec1, H.

Vector borne diseases remain a very heavy burden in large parts of the world. Thanks to advances in genetic engineering, the genetic control of the vector populations may become a new tool to combat these diseases.

Amongst the different genetic drive mechanisms that have been considered to that purpose are the Homing Endonuclease Genes HEGs.

These site-specific selfish genes exploit the recombinational repair system of the cell to copy themselves into a determinate DNA sequence and could be used to knock-out genes in a target species.

To reduce the transmission of malaria, one can aim at depleting the mosquito populations or at making them refractory to the Plasmodium.

Population depletion can be achieved by reducing individual fitness, but also by biasing the sex-ratio towards males, and HEG-based constructs may be engineered for such purposes.

Prior to any practical application, it is necessary to study these strategies, and to determine the most efficient and safest ones.

Using population genetics model we first studied the conditions for spread of such HEG-constructs and thereby investigated the efficiency and reliability of these control strategies depending on properties of the genetic constructs and associated fitness costs.

We then built a model combining population dynamics and genetics, which enabled us to evaluate the impact of these strategies on mosquito densities and on the prevalence of the disease in humans.

M28 Modelling the impacts of climate change on malaria transmission Paul E. Yet despite the considerable sensitivity of malaria transmission to changes in environmental variables, there is still substantial debate as to the exact role that climate plays in driving malaria epidemics.

We illustrate the power of integrated process-based transmission models with explicit links to climate, and embedded within fluctuating environments, as a tool to investigate important aspects of disease transmission, including the roles of biological, environmental and socioeconomic factors driving changes in malaria distribution over time.

The results show that malaria transmission is sensitive to variability in such factors on daily, seasonal, inter-annual and decadal timescales, and that such variability may strongly affect disease emergence, persistence and extinction.

We also demonstrate the role of uncertainty in large-scale climate model output on the predictions of such frameworks, and discuss the associated implications for malaria control, elimination and mitigation.

Emami, L. As red blood cells are the most important source of protein for mosquitoes, any reductions due to anaemia could significantly impede the subsequent fecundity and survival of mosquitoes who feed on affected hosts.

Here laboratory experiments were conducted to assess the impact of variation in human red blood cell density consistent with severe anaemia on the fitness of the African malaria vector An.

These results suggest that contact with anaemic hosts does not reduce the fitness of malaria vectors, and indicates that mosquitoes may exploit resources for reproduction more efficiently from anaemic than normal hosts.

To date, the role of the malaria parasite mitochondrion in energy metabolism and subsequent parasite development has remained somewhat elusive.

There is limited information regarding the respiratory components present during parasite development and their co-operative interactions in response to environmental fluctuations is not understood.

Further, we report the development of a drug discovery programme, generating small molecule inhibitors against the atypical respiratory enzyme, type II NADH:quinone oxidoreductase.

M31 New alleles of pfmdr1 and other markers of P. We present evidence that, since the adoption of ACT-based treatment policies throughout the region, new 40 forms of many of these genes have become apparent.

The possible origins of these alleles, and the potential contribution of new parasite genotypes to the evolution of resistance to ACTs, will be discussed.

The analytical performance of the device was evaluated in the laboratory. The validity of the MOT device was assessed on measurements on live parasitized erythrocytes obtained from a Plasmodium in vitro culture.

In a small clinical trial, stored blood samples from confirmed malaria patients, cases of undifferentiated fever, rheumatic-associated disease or heamoglobinpathies, were tested for Plasmodium infection with RDT and MOT test.

The ease with which the system detected a P. M33 Who transmits malaria? But how well do we really know the human infectious reservoirs for Plasmodium falciparum?

It is often assumed that adults, asymptomatic infections and sub-microscopic gametocytes contribute little to transmission.

With the application of molecular gametocyte detection, it is becoming increasingly clear that these assumptions are wrong and therefore malaria control is often based on incomplete information.

I will discuss why current assumptions about human infectious reservoirs are misleading, what this means for malaria control and for the evolutionary trajectories of parasites.

I will outline future studies required to facilitate successful long-term malaria control, which requires an understanding of factors that determine infectiousness and, therefore, identification and monitoring of human infectious reservoirs.

With little knowledge about the infectious reservoirs for Plasmodium falciparum, the selection pressures that interventions pose on malaria parasites will be difficult to estimate and the long-term impact of interventions on disease and transmission will be difficult to predict.

The life history traits of parasites are affected by their environment, which therefore includes the within-host environment.

Parasites also vary in these traits and thus in how they interact with their environment which can be selected for, sometimes inadvertently.

Parasite life-history traits can have important effects on hosts. I will especially consider the life history traits of parasitic nematodes and show the remarkable degree to which these important aspects of parasite biology are intimately linked to host biology.

S35 Sex ratio and morphological polymorphism in an isolated, endemic Teladorsagia circumcincta population Barbara H.

Craig, Jill G. Teladorsagia circumcincta is a polygamous nematode that exhibits morphological polymorphism. Sex ratio is typically female-biased and the male nematodes occur in association with the genetically similar, minor morphotypes T.

In experimental infections, sex ratio and the proportion of minor male morphs observed have been shown to be influenced by both host and nematode related factors.

As similar investigations from natural systems are rare, this study examined whether sex ratio and minor male morph frequency were associated with host age and sex and nematode infra-population size in the isolated Soay sheep population on St.

Generally, the intensity of Teladorsagia nematodes increased with host age until the age of two years before decreasing. In a year when abundance of nematodes was generally higher, nematode sex ratio was negatively associated with host age and tended to be negatively associated with nematode intensity.

Within the male nematode subpopulation T. The presence of each minor morph was primarily associated with the intensity of male T.

Parasitic infections can deplete host energy stores and alter host trade-offs between survival and reproduction.

Understanding the alteration in these host life history traits is essential if the host population dynamics are to be explained.

In this present study, the survivorship and fecundity of adult German cockroaches Blattella germanica was measured in uninfected individuals and cockroaches infected with a protozoan gut parasite, Gregarina blattarum.

Late stage juveniles were removed from colonies and isolated until completion of their final moult. Newly moulted adults were then paired and monitored for lifetime fecundity and longevity.

All nymphs were removed and the cohorts reared until adulthood. Results show effects on both host survivorship and fecundity under different conditions.

Such individual life history trade-offs are likely to have significant effects on host population dynamics, and this will be explored in future work.

In attempting to make sense of the marked diversity in life-histories found among members of each of two ecologically important parasitic insect groups the parasitoid Hymenoptera and the plant-parasitic Lepidoptera , we have sought to identify an organising trait - one that has a pervasive influence, determining and explaining variation in many other life-history variables.

Establishing a connection between the two strategies could provide a unified conceptual framework for understanding the evolution and diversity of life-history strategies in such insects.

S38 Stress, drugs and the evolution of reproductive restraint in malaria parasites Sarah E. Malaria parasites replicate asexually in their vertebrate hosts, but must reproduce sexually to infect their vectors and transmit to new hosts.

As different parasite stages are required for these functions, the division of resources between these life-history components is a fundamental evolutionary problem.

We test how parasites resolve the trade-off between in-host replication and between-host transmission when exposed to anti-malarial drugs.

We treated multiple drugsensitive and drug-resistant field isolates of the human malaria Plasmodium falciparum with low doses of drugs in vitro.

Previous studies have shown that parasites increase investment in sexual stages when exposed to stressful environmental conditions, such as drugs.

However, we demonstrate the opposite can occur as drug-sensitive parasites facultatively decreased investment in sexual stages in drug-treated cultures.

Furthermore, drug-resistant parasites did not adjust their investment when treated, suggesting that parasites respond to changes in their proliferation rather the presence of drugs.

In contrast to previous studies, we tested parasites from a region where chronic infections contribute significantly to transmission and anti-malarial treatment is common.

We hypothesise that parasite ecology shapes whether in-host survival over between-host transmission are adaptively prioritised when exposed to drug-treatment.

In natural populations, we have found several major-effect polymorphisms controlling resistance to viruses in Drosophila, and at least one of these is matched by polymorphisms that overcome this resistance in viral populations.

These polymorphisms are under strong selection, with resistance sweeping through the fly populations and counter-adaptations sweeping through the virus populations.

We conclude that arms races can drive rapid evolution in both insects and their pathogens. King1, Lynda F. We found that parasites are locally adapted to the shallow-water margins of lakes where sex is more common and not adapted to deeper habitats where sex is rare.

The results are consistent with the Geographic Mosaic Theory and the Red Queen Hypothesis in that sex is associated with coevolutionary hotspots for virulent parasites.

Most host-parasite systems involve multiple steps of the infection process at which host resistance can evolve.

However, despite the ubiquity of multi-step infection processes, their consequences for host-parasite coevolutionary dynamics have yet to be fully explored; standard coevolutionary models typically assume a single-stage infection process e.

We present a novel coevolutionary model with a two-step infection process which accounts for different gene recognition mechanisms underlying each step of the infection process.

This model predicts unexpected and novel patterns of coevolution. Most significantly, we show that multi-step infection can often lead to unique decoupled coevolutionary cycles, where coevolving parasites and hosts undergo gene frequency fluctuations across different regions of their genomes.

Therefore, attempts to detect co-evolutionary dynamics that focus on functionally coupled genetic systems may fail to detect coevolutionary responses.

Our findings may therefore help to explain puzzling patterns of imbalanced levels of polymorphism in functionally linked host and parasite genes.

Overall, we argue that multistep infection processes are common, resulting in important coevolutionary dynamics not considered by current models.

Accounting for such multistep processes will greatly enhance our understanding of the coevolutionary process occurring within many host-parasite systems.

Whilst the divergence observed at some host resistance and parasite infectivity genes is consistent with this, the long time periods typically required to study coevolution have so far prevented any direct empirical test.

Coevolution also resulted in far greater genetic divergence between replicate populations, which was correlated with the range of hosts that coevolved phage were able to infect.

Consistent with this, the most rapidly 44 evolving phage genes under coevolution were those involved in host infection.

These results demonstrate, at both the genomic and phenotypic level, that antagonistic coevolution is a cause of rapid and divergent evolution and is likely to be a major driver of evolutionary change within species.

Theoretical models of the evolution of virulence predict that competition between parasites should select for higher virulence.

While this idea makes intuitive sense, empirical data to support it are rare and equivocal. We investigated the relationship between fitness and virulence during both inter- and intra-specific competition for a fungal parasite of insects, Metarhizium anisopliae.

Contrary to theoretical expectations, competition favoured parasite strains with either a lower or a higher virulence depending on the competitor: when in interspecific competition with an entomopathogenic nematode, Steinernema feltiae, less virulent strains of the fungus were more successful, but when competing against conspecific fungi, more virulent strains were better competitors.

We suggest that in this case the nature of competition direct via toxin production when competing against the nematode, indirect via exploitation of the host when competing against conspecific fungal strains is determining the relationship between virulence and competitive ability.

Meetings Secretary and Hon General Secretary. Lab experiments show that host x parasite genetic interactions have an additional major influence on rates of development, reproduction and survival.

This restricts reproducing parasites to juvenile hosts and to c. Longitudinal studies, based on repeated recaptures of the same host individuals, show that egg output responsible for transmission is maintained in each host age class typically for years before development of immunity that can then protect for over 10 years.

Experimental challenge infection of wild-caught adults confirms effectiveness of this protective immunity. Despite these constraints, the parasite has persisted, dependent on host population recruitment and on the fraction of adult hosts with less effective immunity.

Reece Institutes of Evolution, Immunology and Infection Research, University of Edinburgh, EH9 3JT, UK Both malaria and trypanosome parasites produce specialised stages which are pre-adapted to transmission to the vector and are unable to replicate within the vertebrate host.

These parasites must therefore balance their allocation of resources between within-host replication and betweenhost transmission in order to maximise their fitness.

We have demonstrated that malaria parasites 45 plastically alter their resource allocation strategies in line with changes in genetic diversity of infections and the availability of red blood cell resources, according to the predictions of evolutionary theory.

This includes diverting investment away from between-host transmission when experiencing competition to maximise their ability to compete for host resources.

These findings reveal that an evolutionary-ecology approach, developed to explain the biology of multicellular organisms, can usefully be used to understand the trade-offs parasites face and how, why and when they vary their behaviours.

This allows fine-tuning of existing evolutionary frameworks to formulate predictions for parasite behaviour under certain conditions as well as providing novel tests of the generality of the evolutionary theory.

We describe how this approach has helped us to understand trade-offs in malaria parasites and the next challenge is applying it to other parasites experiencing similar life history trade-offs, such as trypanosomes, to predict their investment strategies for within-host replication and between-host transmission and the resulting implications for virulence.

Fish reduce predation risk and increase foraging success by forming shoals as group members gain benefits shared vigilance, increased mating probability, improved hydrodynamic efficiency compared to solitary individuals.

However, a potential disadvantage of this behaviour is increased parasite transmission. Early work on social organisation within groups focused on interactions between pairs of individuals, but more recently the effects of network interactions and individual variation in behaviour on group structure have been considered.

In the current study, parasitized familiar bold or shy focal guppies Poecilia reticulata , infected with the directly transmitted ectoparasitic worm, Gyrodactylus turnbulli, were introduced into shoals of uninfected bold or shy female conspecifics.

With regard to shoaling behaviour, shy fish formed larger and tighter shoals for longer periods compared to bold fish.

Shy-Bold status of infected focal fish also had a significant effect on the average shoal size of both bold and shy conspecifics.

For parasite transmission, results will be discussed in terms of rate and extent of parasite population growth and transfer between shy-bold hosts.

This is the first study to examine the effect of boldnessshyness on transmission of a fish parasite.

Alexander D. Biomass pyramids Lindeman, are a classic concept in ecology that argues that life can be organized into relatively simple trophic levels where trophic biomass is limited by thermodynamic principles that restrict energy transfer across levels.

The pyramidal pattern represents energy flow in communities across all trophic levels, but a glaring omission is parasite biomass.

Parasitism is one of the most ubiquitous feeding strategies in nature yet it is unclear how parasites fit into the energetic biomass picture of food web organization.

We investigated 24 food chains with trophically transmitted helminth parasites from a stream ecosystem using empirical measures of weight, as well as estimates of biomass calculated from length and width measures of individual parasites.

Pyramidal biomass patterns emerged in food chains containing the most abundant host species, and these were also the hosts that were infected most frequently.

Differences in pyramidal shape can be partly explained by discrepancies between bio-volume estimates and actual measures of parasite mass.

Nonetheless, it is clear that parasite-host associations seem to fit into biomass patterns that are consistent with thermodynamic principles, which restrict energy flow biomass between trophic levels.

Behnke2 1. School of Biology, University of Nottingham, UK Heligmosomoides is well known as a model GI nematode of laboratory mice, and as a common parasite of woodmice, genus Apodemus, throughout Europe.

The relationship between these two forms is less clear. We have suggested previously that Heligmosomoides from laboratory mice is a distinct species, H.

However, the relationship between these two species was unknown, with a strong possibility that H. It is now clear that H. Biogeography 33, , but despite the common ancestral host, H.

It appears that divergence from H. This represents an excellent system in which to examine the molecular changes accompanying host specialisation following a host shift.

Patterns of coinfection may arise because the hosts themselves are intrinsically or temporarily unusually susceptible to all or to particular parasites; or parasites may interact with one another, either positively or negatively.

However, such patterns, and the processes underlying them, have been investigated only rarely in natural populations, especially so amongst aggregates of different microparasite species.

Here, we elaborate, and seek to account for, patterns of coinfection of cowpox virus, Babesia microti, Anaplasma phagocytophilum and Bartonella spp.

We find that these represent a network of strong associations, both positive and negative.

Patterns remain when variations in host susceptibility are accounted for, suggesting that they are mostly generated by interactions between the pathogens themselves rather than by factors associated with exposure risk.

The temporal order of infection can be critical in determining the effect of coinfection on susceptibility, and in general, effects are short-lived, depending on current infection status, rather than previous infections.

Our results highlight the caution that should be exercised when following the standard practice of studying single species of parasite in isolation.

A few hosts become responsible for much of the transmission and the epidemiology is driven by a minority of hosts.

The question is: Why is there so much variation in transmission between hosts? Here, we investigate the role of co-infection in causing such variation.

During the lifetime of any host, they are exposed to a wide diversity of parasites such that at any one time the response to an infection is determined in part by previous infections and in part by their ability to modulate current infections.

This variation may 47 help explain a large component of the variation in infectiousness between hosts. We show strong interactions between the respiratory pathogen Bordetella bronchiseptica and the gut helminth Heligmosomoides polygyrus in mice.

Co-infection increases the number of transmission stages and prolongs the period of shedding in the helminth. Our study demonstrates the fundamental importance of co-infections as one driving factor of variation in transmission between hosts.

Examination of the phylogenetic history of host and bacteria indicate occasional lateral transfer events drive the incidence of Wolbachia.

However, lateral transfer when achieved in the laboratory meets with mixed success; where hosts are distantly related, the infection commonly fails to propagate or show phenotype.

It has recently been discovered that Wolbachia can induce anti-viral resistance in its host. The effects of this resistance on the ability of Wolbachia to propagate is examined in a model exploring the joint population biology of host, Wolbachia and virus.

Natural enemy resistance appears to resolve the Wolbachia paradox, allowing poorly adapted strains to invade which, it is conjectured, then evolve improved transmission and phenotype in their new host species.

S52 Do worms promote or prevent malaria? Using meta-analysis to assess the evidence in mice and men Sarah C. The question of whether coinfecting helminths and malaria parasites interact has attracted much attention in recent years, and is important in the context of intervention strategies for diseases caused by both types of parasite.

The literature now contains numerous empirical studies investigating whether worms affect malarial disease, both in human populations and also in murine lab models, yet firm conclusions have yet to emerge.

Here we report the results of two parallel meta-analyses covering the human and mouse literature respectively in which we quantitatively assess existing evidence on this question.

Specifically, we address 1 whether studies suggest antagonistic or synergistic effects of helminth infection on malarial disease and 2 which factors explain variation in effect size among studies, including biological factors such as host age, helminth species, and the outcome measure used, as well as methodological factors such as experimental design.

Via Celoria 10 Italy. Analysis of the determinants of parasite community structure is a key topic in parasite ecology, with a growing focus on the influence of interaction between co-occurring species.

However, communities are allocated, mainly through qualitative assessment, to one or other of 48 these two extremes, thereby missing the continuum that occurs in nature.

Analysis at a population level may miss the role of intrinsic and extrinsic factors which lead to these differences. We developed a measure of within host contact for each individual parasite and apply this measure to mountain ruminant parasite communities, which are characterized by high seasonal, age and sexual variability.

Mean parasite interaction showed high variability mainly related to temporal effects, with a lesser influence played by host factors.

The largest surviving marsupial carnivore, the Tasmanian devil, Sarcophilus harrisii, is threatened with extinction by a cancer in which the tumour cells themselves are the infectious agent.

The tumour can be considered a clonally reproducing parasitic mammalian cell line. Analysis of extensive field data shows that transmission is frequency, rather than density dependent, which means that this species-specific parasite is capable of causing the extinction of its host.

Management actions being investigated include isolating uninfected animals, disease suppression by removal of all animals showing clinical signs, and attempting to identify genotypes that may show some resistance.

A disease suppression trial on a semi-isolated peninsula has so far failed to halt population decline or to show any decrease in the rate of transition from healthy to infected status.

Tumour cells from one animal are thought to be able to infect another because of very low MHC diversity in the devil population.

However, the disease is now spreading to the north-west of Tasmania where MHC diversity is higher. Prevalence is increasing more slowly in this area than in previously infected locations and age structure remains similar to uninfected populations.

Whether this indicates that some of the north-western genotypes are resistant remains unclear and the outcome of coevolutionary forces on the host parasite interaction is also uncertain.

The ecological circumstances influence, for example, the abundance and virulence of parasites. Moreover, different ecological circumstances may set different costs and thus shape different trade-offs and life-history strategies.

Pied Ficedula hypoleuca and collared flycatchers F. They breed in different parts of Europe, but their distributions overlap in two contact zones.

They experience seasonal changes in both relative fitness and in malaria infection patterns. To investigate whether malaria infected and non-infected 49 birds had occupied different areas on their wintering grounds in Africa, we determined the prevalence and types of malaria blood parasites using a PCR protocol.

Such signatures reflect individual's diet and environmental conditions at the wintering location during feather replacement.

I compare these results with breeding performance data and discuss possible consequences for host species. It produces a distinctive pathology, consisting of white masses of spores visible in the abdomen of the host, which is commonly used as the diagnostic feature when identifying the infection.

Difficulty in obtaining molecular data has resulted in the species only previously being characterised ultrastructurally. Phylogenetic analysis by Bayesian Inference suggests that the species is actually a member of the genus Dictyocoela.

A formal description of Dictyocoela has yet to be published. However, previous studies associate Dictyocoela duebenum with light infections of the gonad and ectodermal tissues, with no mention of the gross muscle pathology associated with T.

Therefore to obtain a true full description, infection in the musculature must also be investigated. It is possible that if Thelohania muelleri is in fact a Dictyocoela parasite that other morphologically similar species such as T.

Otter Lutra lutra populations in the UK have greatly recovered following a severe decline during the s, however further investigation of their parasitic fauna is important and may help prevent future population crashes.

As road-killed otters from England and Wales are routinely collected for post mortem by the Cardiff University Otter Project, gall bladders were screened for parasites.

Two digenean species were recovered from the bile and bile ducts, Pseudamphistomum truncatum and Metorchis albidus.

Both species are thought to have only recently been introduced to the UK and there is no record for either prior to At present, there is no detectable increase in prevalence with year for either parasite.

The pathological damage these parasites cause to the biliary system makes it necessary to monitor their distribution to protect both wild and domestic piscivores against these generalist pathogens.

The presence of these parasites in the UK now provides an ideal opportunity to understand how a pathogen can spread across a novel habitat.

Alison M. Dunn, Jaimie T. Dick, Michael Armstrong, Hazel C. Clarke, Keith D. Farnsworth, Melanie J. Here, we investigate the influence of parasitism on the predatory interactions between native and invasive species in two ongoing UK invasions.

Gammarus pulex is an invasive amphipod that competes with and excludes the native G. Surprisingly, we found that G. The animals displayed Type II functional responses FRs , with the FR for parasitized animals rising more steeply and with a higher asymptote compared with unparasitised individuals.

The increase in the predatory response of infected hosts may enhance the impact of this invader on the recipient community.

Parasitism may also increase the impact of invasion by the American signal crayfish, which is driving the native white clawed crayfish extinct throughout Britain.

Native crayfish infected by the microsporidian parasite Thelohania contejeani showed a lower FR than did uninfected native or invasive species as well as a change in diet.

These changes reduce the ability of the white clawed crayfish to compete with the invasive signal crayfish and may increase the rate of extinction.

Dengue virus, the causative agent of dengue fever and dengue hemorrhagic fever, is widespread throughout tropical and subtropical regions.

The virus exists as four distinct serotypes, all of which have co-circulated in Bangkok for several decades with epidemic outbreaks occurring every years.

Using an epidemic model with stochastic seasonal forcing showing year epidemic oscillations, we demonstrate that moderate cross-protective immunity gives rise to persistent outof-phase oscillations similar to those observed in the data, but that strong or weak cross-protection or cross-enhancement only produces in-phase patterns.

In many regions dengue incidence fluctuates seasonally with few if any infections reported in unfavourable periods.

It has been hypothesized that vertical transmission within the mosquito population allows the virus to persist at these times.

Using a mathematical model we argue that at these infection rates vertical transmission is not an important factor for long term virus persistence.

These approaches achieve different levels of impact on the diseases they are aimed against, depending on host-parasite ecologies for each of disease.

In the case of indirectly transmitted infections, such as lymphatic filariasis and schistosomiasis, these ecologies can be complicated, involving the infection dynamics of several life-stages of the parasite within different hosts.

We investigate the consequences of parasite population dynamics on the control helminth infections. We construct mathematical models of the relevant worm population ecologies, and investigate the effects of density dependent mechanisms on 1 the threshold vector biting rate, 51 below which infection cannot be sustained; 2 the breakpoint parasite density, which implies the existence of a minimum parasite population below which extinction will result; 3 the rate at which the parasite level will change when it is perturbed from its initial level.

Fitting the models to available human and, in some cases, vector data - while quantifying residual uncertainty in the models - shows that parameters relating to the density dependences vary over geographical areas and that these parameters influence estimates of parameters such as R0.

We extract general principles from these results to highlight the importance of considering complex systems dynamics in the design of effective helminth control and elimination programs.

Malaria is a complex vector-borne disease and a major public health burden in endemic regions around the tropic. Non-endemic regions have shown pronounced patterns of increase in incidence and re-emergence in the past three decades.

Despite extensive knowledge accumulated for almost a century on the biology of both the parasite and the mosquito vector, the reasons for these patterns of exacerbation are not well understood.

Climate change, human migrations, and drug resistance are different hypotheses but evaluating these mechanisms from time series data remains elusive.

In this work, we focus on the recent past and on the temporal population dynamics of the disease, to address whether warmer temperatures have already increased the incidence of epidemic malaria in an East African highland.

Our analyzes rely on a monthly time series of confirmed cases from to in the Kericho region of Kenya and on an epidemiological model for the population dynamics of the disease that includes both the human host and the mosquito vector.

Our findings suggest that climate change has already played a role in the exacerbation of malaria in this region. The relative effect of other potential factors acting either in addition to or synergistically to warmer temperatures remains to be carefully evaluated.

Department of Biology and 4. Departments of Biology and Entomology, Pennsylvania State University, University Park PA , USA Understanding interactions between parasites, host resources and other within-host 'ecological' factors is important because they ultimately shape disease outcomes of interest e.

Malaria parasites are known to differ in how they use host resources, for example the four human Plasmodium species invade different age ranges of host red blood cells RBCs.

Such differences in host exploitation traits give rise to different levels of disease severity and are predicted to determine the outcome of competitive interactions between species and strains.

Using a model malaria system P. We find some support for our model predictions, and discover that within-host ecology matters, suggesting that malaria parasites adaptively vary their host exploitation strategies in an adaptive way in response to changes in the within-host environment.

Little1, Karen S. Wagner2, Edoh S. The parasite Onchocerca volvulus has, until recently, been regarded as the cause of a chronic yet non-fatal condition.

New analyses, however, have indicated that in addition to blindness, the parasite can also be directly associated with human mortality.

Such analyses also suggested that the relationship between microfilarial load and excess mortality might be density dependent.

Determining the functional form of such relationship would contribute to quantify the population impact of mass microfilaricidal treatment.

The goodness-of-fit of three candidate functional forms were explored and a saturating exponential type function was deemed to be statistically the best fit.

These conditions will certainly change epidemiological parameters, but could also alter selection on parasite life history traits.

The most obvious difference between hosts living under natural conditions, as compared to farmed hosts, is a significant increase in population density.

It has been shown that host population density is positively correlated with both parasite abundance and species richness.

Moreover, in situations where parasites experience a rapid increase in the number of available hosts, transmission opportunities will be changed, which in turn could select for new combinations of parasite life history traits.

This is of particular concern, since life history traits of parasites could be linked to virulence.

The global rapid increase in fish farming during the last decades could be considered a largescaled experiment providing an opportunity to study the effects of artificially increased host density on parasite epidemiology and evolution.

Using salmon farming as an example, this talk will review the emergence of parasites and pathogens following a dramatic ecological change in the marine environment, and also discuss possible evolutionary implications.

This project represents a considerable challenge to groups focusing on neglected tropical parasitic diseases like onchocerciasis.

Aside from the perceived unsuitability of the DALY to measuring the burden of chronic parasitic infections of the poor, many disease cases go unreported due to unsatisfactory monitoring and registration of morbidity within these populations.

We have updated the disease model to include morbidities associated with onchocercal infection not included in previous estimates. Non-linear relationships between parasitological indicators and various morbidities e.

Despite over fifty years of population-wide vaccination, whooping cough is re-emerging in highly vaccinated populations. Using meta-analysis to assess the evidence in mice and men Sarah C. Patterns remain https://greenandco.co/4k-filme-stream-free/antje-mgnning-bilder.php variations in host susceptibility are accounted for, suggesting that they are mostly generated by interactions between the pathogens themselves rather than by factors associated with exposure opinion Dings Vom Dach are. In all syntheses molecular sulfur is taken from cysteine by a specific please click for source desulfurase, e. Our findings suggest that climate article source has already played a role in the exacerbation of malaria in this region. Emmanuel A. I live here comparison prozac paxil zoloft On a read more related note, I wonder if we will see a natural correction in the COPD and lung cancer rates over the next decades was Grindelwalds Verbrechen Fsk opinion because the smoking rate has declined. Hi Jackson, if you consider, The Office Uk Stream consider a new internet user afterward you have to visit all the time this website and read the updated learn more here at at this place. I must say, as a lot as I enjoyed reading what you had to say, I couldnt help but lose interest after a. Pingback: Www.Ntv and Eve Package. The penis grows in duration visit web page. I think there are lots of more fun sessions up Anabel Möbius for people who scan through your blog.

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Consistent with this, the most rapidly 44 evolving phage genes under coevolution were those involved in host infection. These results demonstrate, at both the genomic and phenotypic level, that antagonistic coevolution is a cause of rapid and divergent evolution and is likely to be a major driver of evolutionary change within species.

Theoretical models of the evolution of virulence predict that competition between parasites should select for higher virulence. While this idea makes intuitive sense, empirical data to support it are rare and equivocal.

We investigated the relationship between fitness and virulence during both inter- and intra-specific competition for a fungal parasite of insects, Metarhizium anisopliae.

Contrary to theoretical expectations, competition favoured parasite strains with either a lower or a higher virulence depending on the competitor: when in interspecific competition with an entomopathogenic nematode, Steinernema feltiae, less virulent strains of the fungus were more successful, but when competing against conspecific fungi, more virulent strains were better competitors.

We suggest that in this case the nature of competition direct via toxin production when competing against the nematode, indirect via exploitation of the host when competing against conspecific fungal strains is determining the relationship between virulence and competitive ability.

Meetings Secretary and Hon General Secretary. Lab experiments show that host x parasite genetic interactions have an additional major influence on rates of development, reproduction and survival.

This restricts reproducing parasites to juvenile hosts and to c. Longitudinal studies, based on repeated recaptures of the same host individuals, show that egg output responsible for transmission is maintained in each host age class typically for years before development of immunity that can then protect for over 10 years.

Experimental challenge infection of wild-caught adults confirms effectiveness of this protective immunity. Despite these constraints, the parasite has persisted, dependent on host population recruitment and on the fraction of adult hosts with less effective immunity.

Reece Institutes of Evolution, Immunology and Infection Research, University of Edinburgh, EH9 3JT, UK Both malaria and trypanosome parasites produce specialised stages which are pre-adapted to transmission to the vector and are unable to replicate within the vertebrate host.

These parasites must therefore balance their allocation of resources between within-host replication and betweenhost transmission in order to maximise their fitness.

We have demonstrated that malaria parasites 45 plastically alter their resource allocation strategies in line with changes in genetic diversity of infections and the availability of red blood cell resources, according to the predictions of evolutionary theory.

This includes diverting investment away from between-host transmission when experiencing competition to maximise their ability to compete for host resources.

These findings reveal that an evolutionary-ecology approach, developed to explain the biology of multicellular organisms, can usefully be used to understand the trade-offs parasites face and how, why and when they vary their behaviours.

This allows fine-tuning of existing evolutionary frameworks to formulate predictions for parasite behaviour under certain conditions as well as providing novel tests of the generality of the evolutionary theory.

We describe how this approach has helped us to understand trade-offs in malaria parasites and the next challenge is applying it to other parasites experiencing similar life history trade-offs, such as trypanosomes, to predict their investment strategies for within-host replication and between-host transmission and the resulting implications for virulence.

Fish reduce predation risk and increase foraging success by forming shoals as group members gain benefits shared vigilance, increased mating probability, improved hydrodynamic efficiency compared to solitary individuals.

However, a potential disadvantage of this behaviour is increased parasite transmission. Early work on social organisation within groups focused on interactions between pairs of individuals, but more recently the effects of network interactions and individual variation in behaviour on group structure have been considered.

In the current study, parasitized familiar bold or shy focal guppies Poecilia reticulata , infected with the directly transmitted ectoparasitic worm, Gyrodactylus turnbulli, were introduced into shoals of uninfected bold or shy female conspecifics.

With regard to shoaling behaviour, shy fish formed larger and tighter shoals for longer periods compared to bold fish.

Shy-Bold status of infected focal fish also had a significant effect on the average shoal size of both bold and shy conspecifics.

For parasite transmission, results will be discussed in terms of rate and extent of parasite population growth and transfer between shy-bold hosts.

This is the first study to examine the effect of boldnessshyness on transmission of a fish parasite. Alexander D.

Biomass pyramids Lindeman, are a classic concept in ecology that argues that life can be organized into relatively simple trophic levels where trophic biomass is limited by thermodynamic principles that restrict energy transfer across levels.

The pyramidal pattern represents energy flow in communities across all trophic levels, but a glaring omission is parasite biomass. Parasitism is one of the most ubiquitous feeding strategies in nature yet it is unclear how parasites fit into the energetic biomass picture of food web organization.

We investigated 24 food chains with trophically transmitted helminth parasites from a stream ecosystem using empirical measures of weight, as well as estimates of biomass calculated from length and width measures of individual parasites.

Pyramidal biomass patterns emerged in food chains containing the most abundant host species, and these were also the hosts that were infected most frequently.

Differences in pyramidal shape can be partly explained by discrepancies between bio-volume estimates and actual measures of parasite mass.

Nonetheless, it is clear that parasite-host associations seem to fit into biomass patterns that are consistent with thermodynamic principles, which restrict energy flow biomass between trophic levels.

Behnke2 1. School of Biology, University of Nottingham, UK Heligmosomoides is well known as a model GI nematode of laboratory mice, and as a common parasite of woodmice, genus Apodemus, throughout Europe.

The relationship between these two forms is less clear. We have suggested previously that Heligmosomoides from laboratory mice is a distinct species, H.

However, the relationship between these two species was unknown, with a strong possibility that H. It is now clear that H.

Biogeography 33, , but despite the common ancestral host, H. It appears that divergence from H. This represents an excellent system in which to examine the molecular changes accompanying host specialisation following a host shift.

Patterns of coinfection may arise because the hosts themselves are intrinsically or temporarily unusually susceptible to all or to particular parasites; or parasites may interact with one another, either positively or negatively.

However, such patterns, and the processes underlying them, have been investigated only rarely in natural populations, especially so amongst aggregates of different microparasite species.

Here, we elaborate, and seek to account for, patterns of coinfection of cowpox virus, Babesia microti, Anaplasma phagocytophilum and Bartonella spp.

We find that these represent a network of strong associations, both positive and negative. Patterns remain when variations in host susceptibility are accounted for, suggesting that they are mostly generated by interactions between the pathogens themselves rather than by factors associated with exposure risk.

The temporal order of infection can be critical in determining the effect of coinfection on susceptibility, and in general, effects are short-lived, depending on current infection status, rather than previous infections.

Our results highlight the caution that should be exercised when following the standard practice of studying single species of parasite in isolation.

A few hosts become responsible for much of the transmission and the epidemiology is driven by a minority of hosts. The question is: Why is there so much variation in transmission between hosts?

Here, we investigate the role of co-infection in causing such variation. During the lifetime of any host, they are exposed to a wide diversity of parasites such that at any one time the response to an infection is determined in part by previous infections and in part by their ability to modulate current infections.

This variation may 47 help explain a large component of the variation in infectiousness between hosts. We show strong interactions between the respiratory pathogen Bordetella bronchiseptica and the gut helminth Heligmosomoides polygyrus in mice.

Co-infection increases the number of transmission stages and prolongs the period of shedding in the helminth.

Our study demonstrates the fundamental importance of co-infections as one driving factor of variation in transmission between hosts. Examination of the phylogenetic history of host and bacteria indicate occasional lateral transfer events drive the incidence of Wolbachia.

However, lateral transfer when achieved in the laboratory meets with mixed success; where hosts are distantly related, the infection commonly fails to propagate or show phenotype.

It has recently been discovered that Wolbachia can induce anti-viral resistance in its host. The effects of this resistance on the ability of Wolbachia to propagate is examined in a model exploring the joint population biology of host, Wolbachia and virus.

Natural enemy resistance appears to resolve the Wolbachia paradox, allowing poorly adapted strains to invade which, it is conjectured, then evolve improved transmission and phenotype in their new host species.

S52 Do worms promote or prevent malaria? Using meta-analysis to assess the evidence in mice and men Sarah C.

The question of whether coinfecting helminths and malaria parasites interact has attracted much attention in recent years, and is important in the context of intervention strategies for diseases caused by both types of parasite.

The literature now contains numerous empirical studies investigating whether worms affect malarial disease, both in human populations and also in murine lab models, yet firm conclusions have yet to emerge.

Here we report the results of two parallel meta-analyses covering the human and mouse literature respectively in which we quantitatively assess existing evidence on this question.

Specifically, we address 1 whether studies suggest antagonistic or synergistic effects of helminth infection on malarial disease and 2 which factors explain variation in effect size among studies, including biological factors such as host age, helminth species, and the outcome measure used, as well as methodological factors such as experimental design.

Via Celoria 10 Italy. Analysis of the determinants of parasite community structure is a key topic in parasite ecology, with a growing focus on the influence of interaction between co-occurring species.

However, communities are allocated, mainly through qualitative assessment, to one or other of 48 these two extremes, thereby missing the continuum that occurs in nature.

Analysis at a population level may miss the role of intrinsic and extrinsic factors which lead to these differences. We developed a measure of within host contact for each individual parasite and apply this measure to mountain ruminant parasite communities, which are characterized by high seasonal, age and sexual variability.

Mean parasite interaction showed high variability mainly related to temporal effects, with a lesser influence played by host factors.

The largest surviving marsupial carnivore, the Tasmanian devil, Sarcophilus harrisii, is threatened with extinction by a cancer in which the tumour cells themselves are the infectious agent.

The tumour can be considered a clonally reproducing parasitic mammalian cell line. Analysis of extensive field data shows that transmission is frequency, rather than density dependent, which means that this species-specific parasite is capable of causing the extinction of its host.

Management actions being investigated include isolating uninfected animals, disease suppression by removal of all animals showing clinical signs, and attempting to identify genotypes that may show some resistance.

A disease suppression trial on a semi-isolated peninsula has so far failed to halt population decline or to show any decrease in the rate of transition from healthy to infected status.

Tumour cells from one animal are thought to be able to infect another because of very low MHC diversity in the devil population.

However, the disease is now spreading to the north-west of Tasmania where MHC diversity is higher. Prevalence is increasing more slowly in this area than in previously infected locations and age structure remains similar to uninfected populations.

Whether this indicates that some of the north-western genotypes are resistant remains unclear and the outcome of coevolutionary forces on the host parasite interaction is also uncertain.

The ecological circumstances influence, for example, the abundance and virulence of parasites.

Moreover, different ecological circumstances may set different costs and thus shape different trade-offs and life-history strategies.

Pied Ficedula hypoleuca and collared flycatchers F. They breed in different parts of Europe, but their distributions overlap in two contact zones.

They experience seasonal changes in both relative fitness and in malaria infection patterns. To investigate whether malaria infected and non-infected 49 birds had occupied different areas on their wintering grounds in Africa, we determined the prevalence and types of malaria blood parasites using a PCR protocol.

Such signatures reflect individual's diet and environmental conditions at the wintering location during feather replacement. I compare these results with breeding performance data and discuss possible consequences for host species.

It produces a distinctive pathology, consisting of white masses of spores visible in the abdomen of the host, which is commonly used as the diagnostic feature when identifying the infection.

Difficulty in obtaining molecular data has resulted in the species only previously being characterised ultrastructurally. Phylogenetic analysis by Bayesian Inference suggests that the species is actually a member of the genus Dictyocoela.

A formal description of Dictyocoela has yet to be published. However, previous studies associate Dictyocoela duebenum with light infections of the gonad and ectodermal tissues, with no mention of the gross muscle pathology associated with T.

Therefore to obtain a true full description, infection in the musculature must also be investigated.

It is possible that if Thelohania muelleri is in fact a Dictyocoela parasite that other morphologically similar species such as T.

Otter Lutra lutra populations in the UK have greatly recovered following a severe decline during the s, however further investigation of their parasitic fauna is important and may help prevent future population crashes.

As road-killed otters from England and Wales are routinely collected for post mortem by the Cardiff University Otter Project, gall bladders were screened for parasites.

Two digenean species were recovered from the bile and bile ducts, Pseudamphistomum truncatum and Metorchis albidus. Both species are thought to have only recently been introduced to the UK and there is no record for either prior to At present, there is no detectable increase in prevalence with year for either parasite.

The pathological damage these parasites cause to the biliary system makes it necessary to monitor their distribution to protect both wild and domestic piscivores against these generalist pathogens.

The presence of these parasites in the UK now provides an ideal opportunity to understand how a pathogen can spread across a novel habitat.

Alison M. Dunn, Jaimie T. Dick, Michael Armstrong, Hazel C. Clarke, Keith D. Farnsworth, Melanie J. Here, we investigate the influence of parasitism on the predatory interactions between native and invasive species in two ongoing UK invasions.

Gammarus pulex is an invasive amphipod that competes with and excludes the native G. Surprisingly, we found that G.

The animals displayed Type II functional responses FRs , with the FR for parasitized animals rising more steeply and with a higher asymptote compared with unparasitised individuals.

The increase in the predatory response of infected hosts may enhance the impact of this invader on the recipient community. Parasitism may also increase the impact of invasion by the American signal crayfish, which is driving the native white clawed crayfish extinct throughout Britain.

Native crayfish infected by the microsporidian parasite Thelohania contejeani showed a lower FR than did uninfected native or invasive species as well as a change in diet.

These changes reduce the ability of the white clawed crayfish to compete with the invasive signal crayfish and may increase the rate of extinction.

Dengue virus, the causative agent of dengue fever and dengue hemorrhagic fever, is widespread throughout tropical and subtropical regions.

The virus exists as four distinct serotypes, all of which have co-circulated in Bangkok for several decades with epidemic outbreaks occurring every years.

Using an epidemic model with stochastic seasonal forcing showing year epidemic oscillations, we demonstrate that moderate cross-protective immunity gives rise to persistent outof-phase oscillations similar to those observed in the data, but that strong or weak cross-protection or cross-enhancement only produces in-phase patterns.

In many regions dengue incidence fluctuates seasonally with few if any infections reported in unfavourable periods.

It has been hypothesized that vertical transmission within the mosquito population allows the virus to persist at these times. Using a mathematical model we argue that at these infection rates vertical transmission is not an important factor for long term virus persistence.

These approaches achieve different levels of impact on the diseases they are aimed against, depending on host-parasite ecologies for each of disease.

In the case of indirectly transmitted infections, such as lymphatic filariasis and schistosomiasis, these ecologies can be complicated, involving the infection dynamics of several life-stages of the parasite within different hosts.

We investigate the consequences of parasite population dynamics on the control helminth infections.

We construct mathematical models of the relevant worm population ecologies, and investigate the effects of density dependent mechanisms on 1 the threshold vector biting rate, 51 below which infection cannot be sustained; 2 the breakpoint parasite density, which implies the existence of a minimum parasite population below which extinction will result; 3 the rate at which the parasite level will change when it is perturbed from its initial level.

Fitting the models to available human and, in some cases, vector data - while quantifying residual uncertainty in the models - shows that parameters relating to the density dependences vary over geographical areas and that these parameters influence estimates of parameters such as R0.

We extract general principles from these results to highlight the importance of considering complex systems dynamics in the design of effective helminth control and elimination programs.

Malaria is a complex vector-borne disease and a major public health burden in endemic regions around the tropic. Non-endemic regions have shown pronounced patterns of increase in incidence and re-emergence in the past three decades.

Despite extensive knowledge accumulated for almost a century on the biology of both the parasite and the mosquito vector, the reasons for these patterns of exacerbation are not well understood.

Climate change, human migrations, and drug resistance are different hypotheses but evaluating these mechanisms from time series data remains elusive.

In this work, we focus on the recent past and on the temporal population dynamics of the disease, to address whether warmer temperatures have already increased the incidence of epidemic malaria in an East African highland.

Our analyzes rely on a monthly time series of confirmed cases from to in the Kericho region of Kenya and on an epidemiological model for the population dynamics of the disease that includes both the human host and the mosquito vector.

Our findings suggest that climate change has already played a role in the exacerbation of malaria in this region. The relative effect of other potential factors acting either in addition to or synergistically to warmer temperatures remains to be carefully evaluated.

Department of Biology and 4. Departments of Biology and Entomology, Pennsylvania State University, University Park PA , USA Understanding interactions between parasites, host resources and other within-host 'ecological' factors is important because they ultimately shape disease outcomes of interest e.

Malaria parasites are known to differ in how they use host resources, for example the four human Plasmodium species invade different age ranges of host red blood cells RBCs.

Such differences in host exploitation traits give rise to different levels of disease severity and are predicted to determine the outcome of competitive interactions between species and strains.

Using a model malaria system P. We find some support for our model predictions, and discover that within-host ecology matters, suggesting that malaria parasites adaptively vary their host exploitation strategies in an adaptive way in response to changes in the within-host environment.

Little1, Karen S. Wagner2, Edoh S. The parasite Onchocerca volvulus has, until recently, been regarded as the cause of a chronic yet non-fatal condition.

New analyses, however, have indicated that in addition to blindness, the parasite can also be directly associated with human mortality.

Such analyses also suggested that the relationship between microfilarial load and excess mortality might be density dependent.

Determining the functional form of such relationship would contribute to quantify the population impact of mass microfilaricidal treatment.

The goodness-of-fit of three candidate functional forms were explored and a saturating exponential type function was deemed to be statistically the best fit.

These conditions will certainly change epidemiological parameters, but could also alter selection on parasite life history traits.

The most obvious difference between hosts living under natural conditions, as compared to farmed hosts, is a significant increase in population density.

It has been shown that host population density is positively correlated with both parasite abundance and species richness.

Moreover, in situations where parasites experience a rapid increase in the number of available hosts, transmission opportunities will be changed, which in turn could select for new combinations of parasite life history traits.

This is of particular concern, since life history traits of parasites could be linked to virulence.

The global rapid increase in fish farming during the last decades could be considered a largescaled experiment providing an opportunity to study the effects of artificially increased host density on parasite epidemiology and evolution.

Using salmon farming as an example, this talk will review the emergence of parasites and pathogens following a dramatic ecological change in the marine environment, and also discuss possible evolutionary implications.

This project represents a considerable challenge to groups focusing on neglected tropical parasitic diseases like onchocerciasis.

Aside from the perceived unsuitability of the DALY to measuring the burden of chronic parasitic infections of the poor, many disease cases go unreported due to unsatisfactory monitoring and registration of morbidity within these populations.

We have updated the disease model to include morbidities associated with onchocercal infection not included in previous estimates. Non-linear relationships between parasitological indicators and various morbidities e.

It is thought to present the second largest health burden of any disease worldwide. Accurate modelling of geographic distribution of the disease at a region level is crucial to guiding the planning of control programmes.

We attempt to map the prevalence of LF infection across Africa using a Bayesian generalised spatial linear model in conjunction with community-level infection data obtained from the published literature.

The model parameters are estimated using Markov chain Monte Carlo techniques. We use the model to explore 1 , the relationship between LF infection prevalence and the environmental variables, 2 assess the biologically plausibility of the estimated functional relationships, and 3 relate this to climate dependency in LF transmission dynamics.

The prevalence map is also used to estimate the total number of people infected with LF in Africa. Finally, we use future climate predictions to investigate the impact global warming could have on future LF spatial distribution, prevalence and burden.

Hayward, Alastair J. Wilson, Jill G. Pilkington, Josephine M. Despite increasing evidence for a decline in immune performance with advancing age in natural populations, it remains unclear how this translates to changes in actual parasite burdens.

Moreover, in populations where individuals may experience heterogeneous and even adverse environmental conditions, there is the potential for large variation in individual life-history trajectories.

We present analysis of gastrointestinal helminth faecal egg count FEC data collected over 20 years from a free-living population of Soay sheep, with the aim of investigating the impact of ageing and environmental conditions on parasite resistance.

Finally, we show that these factors interact, such that individuals that have experienced adverse and stressful conditions show an accelerated age-specific increase in FEC when compared to individuals that have experienced favourable conditions.

Chronological age is thus associated with a decline in parasite resistance, but heterogeneity in experience of 54 environmental conditions and stressors seems an important source of variation in changes in parasite resistance across the host life-history.

S68 Effects of temporal environmental variation on host-parasite dynamics in the Paramecium caudatum - Holospora undulata system Alison B.

It is important to understand how such variation affects epidemiological dynamics in host-parasite systems.

We explored effects of temporal variation in temperature on experimental populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata.

Infected and uninfected populations of 2 P. Variable conditions caused greater declines in host populations at higher temperatures.

This effect was disproportionate for host clone VEN, especially for infected populations. Variable conditions were also detrimental for the parasite causing greater declines in levels of infection.

These results highlight how variable conditions can impact persistence of both host and parasite populations.

They also demonstrate that sign and rates of population decline can depend on host genotype and parasite infection. A, 7eme Etage, CC 7 quai St.

Extensions of this approach are necessary to understand the potential for interaction between different parasite strains within the same host: often they will feel each other's presence only via their effect of the immune system.

The approach also has highlighted the importance of a few neglected questions: modellers typically make the assumption that infections are chronic or acute depending on the disease they want to model but this aspect should actually be an outcome predicted by theory.

In particular, embedded models tend to predict chronic infections: the mechanisms that permit an immune system to eradicate an infection are poorly understood.

Many embedded models are inspired by models for predator-prey interactions but it is worthwhile to point out that models for parasite-immune system interactions be interesting for ecologists.

Long , Alexia T. Karanikas, Eric T. Harvill, Andrew F. Despite over fifty years of population-wide vaccination, whooping cough is re-emerging in highly vaccinated populations.

Although Bordetella pertussis is regarded as the major causative agent of human whooping cough, B. The widely-used acellular whooping cough vaccines aP are composed exclusively of B.

Using a rodent model of infection, we show that aP vaccination helped to clear B. We show that such vaccine-mediated facilitation of B.

Rather, aP vaccination, by reducing lung inflammatory responses measured by cytokine responsiveness in the lung and lung neutrophil recruitment, delayed B.

Our data raise the possibility that aP vaccination can create hosts that are more susceptible to B.

Karen J. Fairlie-Clarke, Tracey J. To determine the relative strength of cross-reactive versus antigen-specific responses, in co-infected mice, we used ELISA to calculate antibody titre from a serial dilution of serum.

We further examined whether cross-reactive responses were targeted toward carbohydrate or protein moieties by treating the parasite antigens with periodate, thus disrupting carbohydrate epitopes by oxidising carbohydrates to aldehydes.

Periodate treatment affected both antigen-specific and cross-reactive responses. For example, if the antigenic distance between two parasites is small the immune system may not perceive them as different and crossreactivity would result.

Maintaining some degree of polyclonality may confer a broader spectrum of protection raising the interesting question of whether production of cross-reactive antibodies might be the optimal response for a host faced with infection by an unpredictable range of parasites.

Here we demonstrate the application of such an approach to generate meaningful immunological profiles for wild mammals.

We sampled a field vole population across a full annual cycle and developed a battery of cellular assays in which functionally different pro- and anti-inflammatory signalling responses transcription factor and cytokine mRNAs were activated and quantified by Q-PCR.

Temporal trends and infection status accounted for a significant proportion of the observed variation in immunological expression.

There were highly significant annual and non-annual temporal immunological trends and systematic differences in the immunological status of animals occurred between equivalent points in the annual cycle Winter and Pinpointing the causes and consequences of such non-seasonal temporal variability may help identify underlying environmental drivers of individual fitness and demographic fluctuation.

However, the majority of such studies focus on wellnourished individuals that are under limited environmental stresses, often infected with only a single experimental pathogen at a time, and are therefore not ecologically valid.

The relatively few studies that have concentrated on natural populations have largely focussed solely on the genetics of the major histocompatibility complex; there is therefore a need to expand research away from the MHC to other immune genes and away from laboratory to natural populations.

Our work has addressed both of these issues by examining the genetic diversity of cytokine genes, key regulators of the immune response, within a well-studied natural population of field voles Microtus agrestis in Kielder Forest, UK.

We used population genetic methods to identify a signature of natural selection acting on several of these genes and then demonstrated that this genetic diversity can lead to phenotypic effects, such as variation in gene expression levels and parasite resistance between individuals.

We conclude that immunogenetic diversity in the vole population is widespread and that host-parasite interactions provide a possible mechanism for its maintenance.

Hanna1, G. Brennan2, D. Sammin3, S. McConnell1, F. Forster1, H. Edgar1, D. Moffett1, M. McConville2, E. Certain well-defined histological changes are recognisable in the reproductive structures of TCBZsensitive flukes following recent TCBZ treatment of the host.

Hence histopathological methods can be used to investigate TCBZ resistance status in field cases of fasciolosis.

Amongst the changes seen in TCBZ-sensitive flukes exposed to metabolites of TCBZ in treated sheep, the development of apoptotic-like bodies in testes, vitelline follicles and ovary predominates.

The cells mainly affected are those undergoing mitosis or meiosis. The occurrence of apoptosis in this situation has been verified by the use of a commercially available kit for immunocytochemical localization of apoptotic cell death.

The method, which relies on recognition of DNA cleavage fragments generated by endonuclease following a trigger event, could improve sensitivity and facilitate quantification of histopathological analysis in the investigation of TCBZ resistance.

Schistosoma haematobium and Schistosoma bovis are blood trematodes that cause diseases in human and ruminant hosts, respectively.

Echinostoma caproni is an intestinal trematode that mainly affects mammals and birds and is used as a model to study helminthiasis.

Sera from S. Our results show that there is differential protein expression between the three species. Furthremore we demonstrated that as expected, the antigen recognition profiles differed between sera from animals infected with S.

Interestingly, we also demostrated that there were some commonly recognised antigens. The relevance of our findings of both differentially expressed proteins and common antigens are discussed in relation to phylogenetic studies, diagnostic tests and vaccine development.

During chronic infection, humans are exposed to several different schistosome lifecycle stages. One hypothesis for the slow development of protective immunity is that exposure to dying longlived adult worms is needed to stimulate a protective response.

Another hypothesis is that a threshold level of antigen must be experienced before a protective response is initiated.

Mathematical models were used to investigate the importance of different parasite lifecycle stages in stimulating antibody responses, and to assess the impact of an antigen threshold.

Model outputs were compared with Schistosoma haematobium field data from Zimbabwe. Results from deterministic models describing mean levels of infection and antibody in homogeneously exposed populations indicated that protective antibody responses stimulated by dying adult worms can reproduce age-infection and age-antibody profiles consistent with field data, but that other lifestages could also be the principal source of protective antigen.

Stochastic individual-based models, which permit heterogeneous exposure, allow us to determine whether these mechanisms can additionally explain observed infection and antibody distributions.

Identifying the mechanisms underlying the development of protective immunity is important for understanding how mass chemotherapy programmes may impact the development of natural immunity, with consequent effects on infection.

Data from experimental models suggest that immunity is also influenced by regulatory T cells Treg , but as yet studies on Treg in human schistosome infections are limited.

We therefore characterized regulatory and 58 activated T cell Tact populations in Zimbabweans aged years exposed to Schistosoma haematobium parasites.

Moreover, there was a significant positive correlation between Treg:Tact ratio and infection intensity. The strongest correlation occurred in the youngest age groups in whom infection was rising and peaking, but the association was lost in the older age group with declining infection levels.

We here describe a completely different mechanism of immune modulation where host lipoproteins serve as transporters of schistosome antigens.

Like many schistosome proteins, these antigens are glycosylated with schistosome specific glycoproteins.

As a result of transfer of schistosome antigens to host lipoproteins, circulating antibodies against schistosome antigens will indirectly bind to these lipoproteins.

We have demonstrated the presence of IgG on low-density lipoprotein particles from serum from infected individuals, whereas no antibodies were found on lipoproteins of healthy controls.

Subsequently, these antibody-opsonised lipoproteins are phagocytosed by immune cells carrying an Fc-receptor.

Indeed, accumulation of lipids within several types of blood derived immune cells occurred in infected individuals only.

In vitro, this lipid accumulation was associated with apoptosis and reduced viability of neutrophils.

The consequences of these lipoprotein binding antibodies for immune cells and for the anti-helminth host response will be discussed.

S79 Eosinophil degranulation against adult Onchocerca ochengi during macrofilaricidal chemotherapy is dependent on depletion of Wolbachia Rowena D.

Hansen1, Germanus S. Bah2, Udo Hetzel1, Vincent N. Tanya2, Alexander J. The basis of the symbiotic relationship between filariae and their Wolbachia endosymbionts is thought to be metabolic, but a role for Wolbachia in defence against immune attack has received little attention.

Neutrophils are attracted to Wolbachia but they are replaced by eosinophils following antibiotic chemotherapy, which degranulate on the worm cuticle.

However, it is not clear whether the eosinophils are involved in killing the filariae or if they are attracted secondarily to dying worms.

In this study, cattle infected with O. In contrast to oxytetracycline, melarsomine had no significant effect on the viability of Wolbachia.

Eosinophil infiltration and degranulation increased significantly only in the oxytetracycline group; whereas nodular gene expression of the chemokine interleukin-8 was lowest in this group.

Moreover, in the early time-points, intense eosinophil degranulation was associated with worm vitality, not degeneration. These data are consistent with a role for eosinophils in antibiotic-mediated killing, and suggest that Wolbachia prevents a local eosinophilia by recruiting neutrophils.

This shapes the way we think about age profiles of infection, distributions of parasites among hosts, and mechanisms regulating parasite populations.

Many large-scale chemotherapy-based programmes are now in place which aim at controlling infection, reducing morbidity, and eliminating infection where deemed possible.

Depending on whether anthelmintics are mass administered or targeted at particular age- or occupational groups, age-infection profiles will be modified; immune responses will be affected; prevalence vs.

Additionally, we need to monitor for changes in drug efficacy and develop novel assays for detection of active infection and exposure as the sensitivity of parasitological indicators decreases, programmes approach transmission breakpoints, and tools are required to ascertain when to stop.

We need to understand how the parasite population biology paradigm is changing if we aim at supporting parasite control efforts effectively.

S81 Porcine parasites in Northern Ireland: incidence, distribution and correlation with management and control strategies J. Black1, J.

Marks1, A. Endoparasitic worms inflict a huge economic burden on pig production through reduced growth, poor feed conversion efficiencies and higher medication costs.

As yet, anthelmintic resistance has not been reported in swine herds in the UK or Ireland. However, benzimidazole and levamisole resistant nematodes have been identified from herds in Germany concurring with the situation in other nematode parasites of sheep and cattle where multi-drug resistance is rife.

The aim of this study is to investigate the prevalence and distribution of helminth parasites in pig units across Northern Ireland N.

Other species identified included: Hyostrongylus rubidis, Oesophagostumum dentatum, Metastrongylus apri, Trichuris suis and Fasciola hepatica.

These findings indicate that despite good husbandry practice, high-levels of worms are commonplace on most pig units in N.

Echinococcus granulosus is a dog tapeworm that causes the zoonotic disease, cystic echinococcosis. Canine echinococcosis appears to have re-emerged in Powys, Wales following a control programme in the s Buishi et al.

The Office of the Chief Veterinary Officer and 60 the Department for Public Health and Health Professions in the Welsh Assembly Government jointly funded a pilot dog worming campaign as a preventative public health measure.

To evaluate the impact and efficiency of a short-term supervised dog dosing scheme, collection of faecal samples on farm visits and worming of dogs with praziquantel commenced in South Powys in May In Year 1, approximately canid faecal samples were collected from registered farms and delivered to the University of Salford to be tested.

In total faecal samples were tested by coproELISA, of these samples were collected at baseline and were found to have a coproantigen prevalence of A total of samples tested after 3 treatments gave a coproantigen prevalence of 0.

The study will continue to compare the coproantigen prevalence over one year after cessation of dosing. Nicotinic acetylcholine receptors nAChRs are significant drug targets for parasitic nematodes, and several sub-types of these receptors are present on body wall muscle.

We recently identified a novel nAChR subunit gene, acr, from Ascaris suum. A survey of parasitic nematodes, using a combination of sequence data and primary material, demonstrates that acr is conserved in several parasitic species from clades III and V, including Brugia malayi, Haemonchus contortus and Dirofilaria immitis.

To date however, no evidence has been found of acr in any free-living or plant parasitic nematode. A specific antibody against the Asu-ACR subunit was produced; immunocytochemistry on native tissue showed that the subunit was expressed in the head muscle of A.

Sequence similarities with other nAChRs and computer modelling predicted that ACR was capable of forming a homomeric channel.

In vitro expression of ACR in the Xenopus oocyte expression system confirmed this prediction and showed that the receptor responded to both acetylcholine and nicotine, but was not sensitive to levamisole.

The pharmacology and function of this new receptor are being investigated further. S84 Vaccination of rats against fasciolosis by a multivalent vaccine of stage-specific cathepsin proteases induces significant protection Ramamoorthi Jayaraj1, David Piedrafita2, Kemperley Dynon2, Rudi Grams3, Terry W.

Fasciola hepatica produces cathepsin B and cathepsin L in their excretory-secretory material.

These proteases are proposed to be key virulence factors for parasite infection and are targets for vaccination.

Cathepsin B isoforms are predominantly released in the juvenile life cycle stage while different cathepsin L isoforms are released throughout the cycle.

Three proteases cathepsin L5, cathepsin L1g and cathepsin B1 were expressed using cDNAs isolated from adult, metacercariae and juvenile flukes, respectively.

Each was used singly or in combination to vaccinate rats that were challenged with F. All vaccinated groups yielded significantly fewer and smaller flukes than the control group, suggesting vaccination retarded liver fluke development.

Kimber, Chuanzhe Song, Jack M. Gallup, Tim A. Bartholomay Departments of Biomedical Sciences and Entomology, Iowa State University, Ames, IA USA Diseases caused by parasitic nematodes perpetuate socioeconomic instability in developing countries by inflicting crippling morbidity and significant mortality.

One reason for the persistence of these diseases is an inadequate portfolio of effective drugs; new, more effective compounds are needed.

A major obstacle to their development is the lack of available tools to validate potential novel drug targets in parasitic nematodes.

RNA Interference RNAi is a tool that allows researchers to suppress genes of interest in experimental organisms or tissues and has become standard for target validation in drug development but a reliable and reproducible protocol for parasitic nematodes has yet to be established.

Here we describe an innovative RNAi strategy to study gene function and validate drug targets in parasitic nematodes.

Our approach uses the filarial nematode Brugia malayi as a model and targets developmental stages of this parasite whilst still in the mosquito host.

We can profoundly suppress expression of a cathepsin-L-like gene using both short interfering RNA and long double stranded RNA injected directly into infected mosquitoes.

Cathepsin L-like suppression elicits aberrant worm phenotypes with motility defects and reduced transmission potential.

Finally we present evidence that other genes are susceptible to this approach. Since completion of the Caenorhabditis elegans genome sequence the generation of genomic and transcriptomic datasets for nematode parasites has evolved relatively slowly.

More recent advances in power sequencing have fuelled a significant expansion in transcriptomic datasets and publication of the first genome sequences for nematode parasites.

An additional stimulus has been the discovery of RNA interference RNAi and its potential to allow gene function or, drug target validation studies in organisms previously refractory to reverse genetic manipulation.

Aiming to decipher the functional context of these sequence data, parasitologists have attempted to adapt RNAi for use in parasitic nematodes.

While progress has been significant in plant parasites, gene silencing in animal-parasitic nematodes has floundered under the difficulties associated with triggering robust transcript knockdown.

To test this we used 77 C. Although preliminary screens indicate that most proteins are reasonably well conserved, notable omissions include proteins responsible for RNAi uptake and spreading.

Warnock, N. Marks, A. RNA interference RNAi provides a reverse genetics platform which facilitates investigations into gene function, providing opportunities for drug target identification and validation.

However, despite initially encouraging results from the scientific community working on animal parasitic nematodes APNs , recent experimentation has revealed that the RNAi response is not robust across all APN species.

Our approach includes the examination of 9 gene transcript targets whose selection was based on transcript abundance, localisation neuronal, gut, reproductive or global tissue expression and previous success in other APN-RNAi experiments.

DsRNAs were delivered to the infective stage of A. Our results indicate variable susceptibility of the targets; no trend was observed between transcript abundance or localisation and susceptibility.

In parasitic nematodes RNAi has proven to be less effective. We have carried out a detailed RNAi study in the sheep gastrointestinal nematode Haemonchus contortus to examine why some genes seem to be more susceptible to RNAi silencing than other genes.

We have obtained specific and reproducible silencing for several genes including the H. Silencing of H11 transcript can be achieved following soaking of L3 infective stage larvae in dsRNA for 24 hours.

Larvae are viable after this treatment with no detrimental effects observed in vitro. To examine any in vivo effects of H11 silencing, sheep were infected with larvae pre-treated with dsRNA to H11 or to a control C.

This is the first demonstration of an in vivo effect following gene silencing in an animal parasitic nematode. This study reveals that putative Meloidogyne incognita orthologues of Caenorhabditis elegans cillial motor proteins, Mi-che-3 and Mi-osm-3, perform functionally comparable roles in the amphids, the main nematode chemosensory organs.

We demonstrate that transcript knockdown by RNAi can recapitulate the aberrant response to chemotactic gradients characteristic of the respective C.

Our sensory assays indicate that knockdown of either transcript using short interfering si RNAs, inhibits the normal attraction and repulsion responses of M.

In addition, we find that the neuropeptide encoding Mi-flp, which is involved in the social feeding phenotype of C. This work demonstrates that RNAi can recapitulate null-phenotypes of functionally conserved amphid proteins in the root knot nematode M.

Cameron, A. Mousley, N. With control relying heavy on triclabendazole, resistance is well established and highlights the need for novel control options.

Within the genus Fasciola there are at least eighteen sub-types of FheCL which show remarkable sequence conservation. Structural and bioinformatic studies along with the identification of enzyme specificity have allowed the division of multiple cathepsin Ls into sub-categories designated clades; these appear to have distinct functional roles.

Promiscuous siRNAs have been designed to silence multiple clades simultaneously, whereas the selective siRNAs are clade specific.

In addition to qPCR, the impact of silencing on phenotype has been examined. The preliminary data highlight variation in silencing susceptibilities and efficiencies and demonstrate the need to optimize individual siRNAs prior to functional assessments.

Stevenson1, J. Dalzell1, C. Until recently, carbamate and organophosphate-based nematicides have been used to control plant parasitic nematodes, but have been withdrawn due to environmental concerns.

In an effort to investigate if the RNAi-susceptibility of potato cyst nematode gene transcripts is tissuedependent, we set out to knockdown G.

Initially, genes expressed exclusively in neuronal cells of the head ganglia Gp-ace-2 encoding acetylcholinesterase or in the subventral oesophageal gland cells Gp-cell-1 and Gpcm-1 encoding B-1, 4 endoglucanase [cellulase] and chorismate mutase, respectively.

The end goal will be to breed plants expressing nematode-specific dsRNA or siRNAs in planta which will be resistant to parasitic nematode infestation.

Our aim is to assess whether ivermectin sensitivity in this strain can be restored by expressing GluCl subunit cDNA from Haemonchus contortus, a parasitic 64 nematode from the same clade as C.

We have used particle bombardment to create transgenic C. Dose response curves for ivermectin were comparable between the Hco-avrB strain and an avr; glc-1 mutant, indicating that the H.

In contrast, the triple mutant containing Hco-avrA cDNA did not show any rescue of ivermectin sensitivity Our data using C.

A few hosts become responsible for much of the transmission and the epidemiology is driven by a minority of hosts. The question is: Why is there so much variation in transmission between hosts?

Here, we investigate the role of co-infection in causing such variation. During the lifetime of any host, they are exposed to a wide diversity of parasites such that at any one time the response to an infection is determined in part by previous infections and in part by their ability to modulate current infections.

This variation may 47 help explain a large component of the variation in infectiousness between hosts. We show strong interactions between the respiratory pathogen Bordetella bronchiseptica and the gut helminth Heligmosomoides polygyrus in mice.

Co-infection increases the number of transmission stages and prolongs the period of shedding in the helminth.

Our study demonstrates the fundamental importance of co-infections as one driving factor of variation in transmission between hosts.

Examination of the phylogenetic history of host and bacteria indicate occasional lateral transfer events drive the incidence of Wolbachia.

However, lateral transfer when achieved in the laboratory meets with mixed success; where hosts are distantly related, the infection commonly fails to propagate or show phenotype.

It has recently been discovered that Wolbachia can induce anti-viral resistance in its host. The effects of this resistance on the ability of Wolbachia to propagate is examined in a model exploring the joint population biology of host, Wolbachia and virus.

Natural enemy resistance appears to resolve the Wolbachia paradox, allowing poorly adapted strains to invade which, it is conjectured, then evolve improved transmission and phenotype in their new host species.

S52 Do worms promote or prevent malaria? Using meta-analysis to assess the evidence in mice and men Sarah C. The question of whether coinfecting helminths and malaria parasites interact has attracted much attention in recent years, and is important in the context of intervention strategies for diseases caused by both types of parasite.

The literature now contains numerous empirical studies investigating whether worms affect malarial disease, both in human populations and also in murine lab models, yet firm conclusions have yet to emerge.

Here we report the results of two parallel meta-analyses covering the human and mouse literature respectively in which we quantitatively assess existing evidence on this question.

Specifically, we address 1 whether studies suggest antagonistic or synergistic effects of helminth infection on malarial disease and 2 which factors explain variation in effect size among studies, including biological factors such as host age, helminth species, and the outcome measure used, as well as methodological factors such as experimental design.

Via Celoria 10 Italy. Analysis of the determinants of parasite community structure is a key topic in parasite ecology, with a growing focus on the influence of interaction between co-occurring species.

However, communities are allocated, mainly through qualitative assessment, to one or other of 48 these two extremes, thereby missing the continuum that occurs in nature.

Analysis at a population level may miss the role of intrinsic and extrinsic factors which lead to these differences.

We developed a measure of within host contact for each individual parasite and apply this measure to mountain ruminant parasite communities, which are characterized by high seasonal, age and sexual variability.

Mean parasite interaction showed high variability mainly related to temporal effects, with a lesser influence played by host factors.

The largest surviving marsupial carnivore, the Tasmanian devil, Sarcophilus harrisii, is threatened with extinction by a cancer in which the tumour cells themselves are the infectious agent.

The tumour can be considered a clonally reproducing parasitic mammalian cell line. Analysis of extensive field data shows that transmission is frequency, rather than density dependent, which means that this species-specific parasite is capable of causing the extinction of its host.

Management actions being investigated include isolating uninfected animals, disease suppression by removal of all animals showing clinical signs, and attempting to identify genotypes that may show some resistance.

A disease suppression trial on a semi-isolated peninsula has so far failed to halt population decline or to show any decrease in the rate of transition from healthy to infected status.

Tumour cells from one animal are thought to be able to infect another because of very low MHC diversity in the devil population.

However, the disease is now spreading to the north-west of Tasmania where MHC diversity is higher. Prevalence is increasing more slowly in this area than in previously infected locations and age structure remains similar to uninfected populations.

Whether this indicates that some of the north-western genotypes are resistant remains unclear and the outcome of coevolutionary forces on the host parasite interaction is also uncertain.

The ecological circumstances influence, for example, the abundance and virulence of parasites. Moreover, different ecological circumstances may set different costs and thus shape different trade-offs and life-history strategies.

Pied Ficedula hypoleuca and collared flycatchers F. They breed in different parts of Europe, but their distributions overlap in two contact zones.

They experience seasonal changes in both relative fitness and in malaria infection patterns. To investigate whether malaria infected and non-infected 49 birds had occupied different areas on their wintering grounds in Africa, we determined the prevalence and types of malaria blood parasites using a PCR protocol.

Such signatures reflect individual's diet and environmental conditions at the wintering location during feather replacement.

I compare these results with breeding performance data and discuss possible consequences for host species.

It produces a distinctive pathology, consisting of white masses of spores visible in the abdomen of the host, which is commonly used as the diagnostic feature when identifying the infection.

Difficulty in obtaining molecular data has resulted in the species only previously being characterised ultrastructurally.

Phylogenetic analysis by Bayesian Inference suggests that the species is actually a member of the genus Dictyocoela.

A formal description of Dictyocoela has yet to be published. However, previous studies associate Dictyocoela duebenum with light infections of the gonad and ectodermal tissues, with no mention of the gross muscle pathology associated with T.

Therefore to obtain a true full description, infection in the musculature must also be investigated.

It is possible that if Thelohania muelleri is in fact a Dictyocoela parasite that other morphologically similar species such as T.

Otter Lutra lutra populations in the UK have greatly recovered following a severe decline during the s, however further investigation of their parasitic fauna is important and may help prevent future population crashes.

As road-killed otters from England and Wales are routinely collected for post mortem by the Cardiff University Otter Project, gall bladders were screened for parasites.

Two digenean species were recovered from the bile and bile ducts, Pseudamphistomum truncatum and Metorchis albidus. Both species are thought to have only recently been introduced to the UK and there is no record for either prior to At present, there is no detectable increase in prevalence with year for either parasite.

The pathological damage these parasites cause to the biliary system makes it necessary to monitor their distribution to protect both wild and domestic piscivores against these generalist pathogens.

The presence of these parasites in the UK now provides an ideal opportunity to understand how a pathogen can spread across a novel habitat.

Alison M. Dunn, Jaimie T. Dick, Michael Armstrong, Hazel C. Clarke, Keith D. Farnsworth, Melanie J. Here, we investigate the influence of parasitism on the predatory interactions between native and invasive species in two ongoing UK invasions.

Gammarus pulex is an invasive amphipod that competes with and excludes the native G. Surprisingly, we found that G. The animals displayed Type II functional responses FRs , with the FR for parasitized animals rising more steeply and with a higher asymptote compared with unparasitised individuals.

The increase in the predatory response of infected hosts may enhance the impact of this invader on the recipient community. Parasitism may also increase the impact of invasion by the American signal crayfish, which is driving the native white clawed crayfish extinct throughout Britain.

Native crayfish infected by the microsporidian parasite Thelohania contejeani showed a lower FR than did uninfected native or invasive species as well as a change in diet.

These changes reduce the ability of the white clawed crayfish to compete with the invasive signal crayfish and may increase the rate of extinction.

Dengue virus, the causative agent of dengue fever and dengue hemorrhagic fever, is widespread throughout tropical and subtropical regions.

The virus exists as four distinct serotypes, all of which have co-circulated in Bangkok for several decades with epidemic outbreaks occurring every years.

Using an epidemic model with stochastic seasonal forcing showing year epidemic oscillations, we demonstrate that moderate cross-protective immunity gives rise to persistent outof-phase oscillations similar to those observed in the data, but that strong or weak cross-protection or cross-enhancement only produces in-phase patterns.

In many regions dengue incidence fluctuates seasonally with few if any infections reported in unfavourable periods. It has been hypothesized that vertical transmission within the mosquito population allows the virus to persist at these times.

Using a mathematical model we argue that at these infection rates vertical transmission is not an important factor for long term virus persistence.

These approaches achieve different levels of impact on the diseases they are aimed against, depending on host-parasite ecologies for each of disease.

In the case of indirectly transmitted infections, such as lymphatic filariasis and schistosomiasis, these ecologies can be complicated, involving the infection dynamics of several life-stages of the parasite within different hosts.

We investigate the consequences of parasite population dynamics on the control helminth infections. We construct mathematical models of the relevant worm population ecologies, and investigate the effects of density dependent mechanisms on 1 the threshold vector biting rate, 51 below which infection cannot be sustained; 2 the breakpoint parasite density, which implies the existence of a minimum parasite population below which extinction will result; 3 the rate at which the parasite level will change when it is perturbed from its initial level.

Fitting the models to available human and, in some cases, vector data - while quantifying residual uncertainty in the models - shows that parameters relating to the density dependences vary over geographical areas and that these parameters influence estimates of parameters such as R0.

We extract general principles from these results to highlight the importance of considering complex systems dynamics in the design of effective helminth control and elimination programs.

Malaria is a complex vector-borne disease and a major public health burden in endemic regions around the tropic. Non-endemic regions have shown pronounced patterns of increase in incidence and re-emergence in the past three decades.

Despite extensive knowledge accumulated for almost a century on the biology of both the parasite and the mosquito vector, the reasons for these patterns of exacerbation are not well understood.

Climate change, human migrations, and drug resistance are different hypotheses but evaluating these mechanisms from time series data remains elusive.

In this work, we focus on the recent past and on the temporal population dynamics of the disease, to address whether warmer temperatures have already increased the incidence of epidemic malaria in an East African highland.

Our analyzes rely on a monthly time series of confirmed cases from to in the Kericho region of Kenya and on an epidemiological model for the population dynamics of the disease that includes both the human host and the mosquito vector.

Our findings suggest that climate change has already played a role in the exacerbation of malaria in this region. The relative effect of other potential factors acting either in addition to or synergistically to warmer temperatures remains to be carefully evaluated.

Department of Biology and 4. Departments of Biology and Entomology, Pennsylvania State University, University Park PA , USA Understanding interactions between parasites, host resources and other within-host 'ecological' factors is important because they ultimately shape disease outcomes of interest e.

Malaria parasites are known to differ in how they use host resources, for example the four human Plasmodium species invade different age ranges of host red blood cells RBCs.

Such differences in host exploitation traits give rise to different levels of disease severity and are predicted to determine the outcome of competitive interactions between species and strains.

Using a model malaria system P. We find some support for our model predictions, and discover that within-host ecology matters, suggesting that malaria parasites adaptively vary their host exploitation strategies in an adaptive way in response to changes in the within-host environment.

Little1, Karen S. Wagner2, Edoh S. The parasite Onchocerca volvulus has, until recently, been regarded as the cause of a chronic yet non-fatal condition.

New analyses, however, have indicated that in addition to blindness, the parasite can also be directly associated with human mortality.

Such analyses also suggested that the relationship between microfilarial load and excess mortality might be density dependent.

Determining the functional form of such relationship would contribute to quantify the population impact of mass microfilaricidal treatment.

The goodness-of-fit of three candidate functional forms were explored and a saturating exponential type function was deemed to be statistically the best fit.

These conditions will certainly change epidemiological parameters, but could also alter selection on parasite life history traits.

The most obvious difference between hosts living under natural conditions, as compared to farmed hosts, is a significant increase in population density.

It has been shown that host population density is positively correlated with both parasite abundance and species richness.

Moreover, in situations where parasites experience a rapid increase in the number of available hosts, transmission opportunities will be changed, which in turn could select for new combinations of parasite life history traits.

This is of particular concern, since life history traits of parasites could be linked to virulence. The global rapid increase in fish farming during the last decades could be considered a largescaled experiment providing an opportunity to study the effects of artificially increased host density on parasite epidemiology and evolution.

Using salmon farming as an example, this talk will review the emergence of parasites and pathogens following a dramatic ecological change in the marine environment, and also discuss possible evolutionary implications.

This project represents a considerable challenge to groups focusing on neglected tropical parasitic diseases like onchocerciasis.

Aside from the perceived unsuitability of the DALY to measuring the burden of chronic parasitic infections of the poor, many disease cases go unreported due to unsatisfactory monitoring and registration of morbidity within these populations.

We have updated the disease model to include morbidities associated with onchocercal infection not included in previous estimates.

Non-linear relationships between parasitological indicators and various morbidities e. It is thought to present the second largest health burden of any disease worldwide.

Accurate modelling of geographic distribution of the disease at a region level is crucial to guiding the planning of control programmes.

We attempt to map the prevalence of LF infection across Africa using a Bayesian generalised spatial linear model in conjunction with community-level infection data obtained from the published literature.

The model parameters are estimated using Markov chain Monte Carlo techniques. We use the model to explore 1 , the relationship between LF infection prevalence and the environmental variables, 2 assess the biologically plausibility of the estimated functional relationships, and 3 relate this to climate dependency in LF transmission dynamics.

The prevalence map is also used to estimate the total number of people infected with LF in Africa. Finally, we use future climate predictions to investigate the impact global warming could have on future LF spatial distribution, prevalence and burden.

Hayward, Alastair J. Wilson, Jill G. Pilkington, Josephine M. Despite increasing evidence for a decline in immune performance with advancing age in natural populations, it remains unclear how this translates to changes in actual parasite burdens.

Moreover, in populations where individuals may experience heterogeneous and even adverse environmental conditions, there is the potential for large variation in individual life-history trajectories.

We present analysis of gastrointestinal helminth faecal egg count FEC data collected over 20 years from a free-living population of Soay sheep, with the aim of investigating the impact of ageing and environmental conditions on parasite resistance.

Finally, we show that these factors interact, such that individuals that have experienced adverse and stressful conditions show an accelerated age-specific increase in FEC when compared to individuals that have experienced favourable conditions.

Chronological age is thus associated with a decline in parasite resistance, but heterogeneity in experience of 54 environmental conditions and stressors seems an important source of variation in changes in parasite resistance across the host life-history.

S68 Effects of temporal environmental variation on host-parasite dynamics in the Paramecium caudatum - Holospora undulata system Alison B.

It is important to understand how such variation affects epidemiological dynamics in host-parasite systems. We explored effects of temporal variation in temperature on experimental populations of the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata.

Infected and uninfected populations of 2 P. Variable conditions caused greater declines in host populations at higher temperatures.

This effect was disproportionate for host clone VEN, especially for infected populations. Variable conditions were also detrimental for the parasite causing greater declines in levels of infection.

These results highlight how variable conditions can impact persistence of both host and parasite populations.

They also demonstrate that sign and rates of population decline can depend on host genotype and parasite infection. A, 7eme Etage, CC 7 quai St.

Extensions of this approach are necessary to understand the potential for interaction between different parasite strains within the same host: often they will feel each other's presence only via their effect of the immune system.

The approach also has highlighted the importance of a few neglected questions: modellers typically make the assumption that infections are chronic or acute depending on the disease they want to model but this aspect should actually be an outcome predicted by theory.

In particular, embedded models tend to predict chronic infections: the mechanisms that permit an immune system to eradicate an infection are poorly understood.

Many embedded models are inspired by models for predator-prey interactions but it is worthwhile to point out that models for parasite-immune system interactions be interesting for ecologists.

Long , Alexia T. Karanikas, Eric T. Harvill, Andrew F. Despite over fifty years of population-wide vaccination, whooping cough is re-emerging in highly vaccinated populations.

Although Bordetella pertussis is regarded as the major causative agent of human whooping cough, B. The widely-used acellular whooping cough vaccines aP are composed exclusively of B.

Using a rodent model of infection, we show that aP vaccination helped to clear B. We show that such vaccine-mediated facilitation of B.

Rather, aP vaccination, by reducing lung inflammatory responses measured by cytokine responsiveness in the lung and lung neutrophil recruitment, delayed B.

Our data raise the possibility that aP vaccination can create hosts that are more susceptible to B.

Karen J. Fairlie-Clarke, Tracey J. To determine the relative strength of cross-reactive versus antigen-specific responses, in co-infected mice, we used ELISA to calculate antibody titre from a serial dilution of serum.

We further examined whether cross-reactive responses were targeted toward carbohydrate or protein moieties by treating the parasite antigens with periodate, thus disrupting carbohydrate epitopes by oxidising carbohydrates to aldehydes.

Periodate treatment affected both antigen-specific and cross-reactive responses. For example, if the antigenic distance between two parasites is small the immune system may not perceive them as different and crossreactivity would result.

Maintaining some degree of polyclonality may confer a broader spectrum of protection raising the interesting question of whether production of cross-reactive antibodies might be the optimal response for a host faced with infection by an unpredictable range of parasites.

Here we demonstrate the application of such an approach to generate meaningful immunological profiles for wild mammals.

We sampled a field vole population across a full annual cycle and developed a battery of cellular assays in which functionally different pro- and anti-inflammatory signalling responses transcription factor and cytokine mRNAs were activated and quantified by Q-PCR.

Temporal trends and infection status accounted for a significant proportion of the observed variation in immunological expression.

There were highly significant annual and non-annual temporal immunological trends and systematic differences in the immunological status of animals occurred between equivalent points in the annual cycle Winter and Pinpointing the causes and consequences of such non-seasonal temporal variability may help identify underlying environmental drivers of individual fitness and demographic fluctuation.

However, the majority of such studies focus on wellnourished individuals that are under limited environmental stresses, often infected with only a single experimental pathogen at a time, and are therefore not ecologically valid.

The relatively few studies that have concentrated on natural populations have largely focussed solely on the genetics of the major histocompatibility complex; there is therefore a need to expand research away from the MHC to other immune genes and away from laboratory to natural populations.

Our work has addressed both of these issues by examining the genetic diversity of cytokine genes, key regulators of the immune response, within a well-studied natural population of field voles Microtus agrestis in Kielder Forest, UK.

We used population genetic methods to identify a signature of natural selection acting on several of these genes and then demonstrated that this genetic diversity can lead to phenotypic effects, such as variation in gene expression levels and parasite resistance between individuals.

We conclude that immunogenetic diversity in the vole population is widespread and that host-parasite interactions provide a possible mechanism for its maintenance.

Hanna1, G. Brennan2, D. Sammin3, S. McConnell1, F. Forster1, H. Edgar1, D. Moffett1, M. McConville2, E. Certain well-defined histological changes are recognisable in the reproductive structures of TCBZsensitive flukes following recent TCBZ treatment of the host.

Hence histopathological methods can be used to investigate TCBZ resistance status in field cases of fasciolosis. Amongst the changes seen in TCBZ-sensitive flukes exposed to metabolites of TCBZ in treated sheep, the development of apoptotic-like bodies in testes, vitelline follicles and ovary predominates.

The cells mainly affected are those undergoing mitosis or meiosis. The occurrence of apoptosis in this situation has been verified by the use of a commercially available kit for immunocytochemical localization of apoptotic cell death.

The method, which relies on recognition of DNA cleavage fragments generated by endonuclease following a trigger event, could improve sensitivity and facilitate quantification of histopathological analysis in the investigation of TCBZ resistance.

Schistosoma haematobium and Schistosoma bovis are blood trematodes that cause diseases in human and ruminant hosts, respectively. Echinostoma caproni is an intestinal trematode that mainly affects mammals and birds and is used as a model to study helminthiasis.

Sera from S. Our results show that there is differential protein expression between the three species. Furthremore we demonstrated that as expected, the antigen recognition profiles differed between sera from animals infected with S.

Interestingly, we also demostrated that there were some commonly recognised antigens. The relevance of our findings of both differentially expressed proteins and common antigens are discussed in relation to phylogenetic studies, diagnostic tests and vaccine development.

During chronic infection, humans are exposed to several different schistosome lifecycle stages. One hypothesis for the slow development of protective immunity is that exposure to dying longlived adult worms is needed to stimulate a protective response.

Another hypothesis is that a threshold level of antigen must be experienced before a protective response is initiated. Mathematical models were used to investigate the importance of different parasite lifecycle stages in stimulating antibody responses, and to assess the impact of an antigen threshold.

Model outputs were compared with Schistosoma haematobium field data from Zimbabwe. Results from deterministic models describing mean levels of infection and antibody in homogeneously exposed populations indicated that protective antibody responses stimulated by dying adult worms can reproduce age-infection and age-antibody profiles consistent with field data, but that other lifestages could also be the principal source of protective antigen.

Stochastic individual-based models, which permit heterogeneous exposure, allow us to determine whether these mechanisms can additionally explain observed infection and antibody distributions.

Identifying the mechanisms underlying the development of protective immunity is important for understanding how mass chemotherapy programmes may impact the development of natural immunity, with consequent effects on infection.

Data from experimental models suggest that immunity is also influenced by regulatory T cells Treg , but as yet studies on Treg in human schistosome infections are limited.

We therefore characterized regulatory and 58 activated T cell Tact populations in Zimbabweans aged years exposed to Schistosoma haematobium parasites.

Moreover, there was a significant positive correlation between Treg:Tact ratio and infection intensity.

The strongest correlation occurred in the youngest age groups in whom infection was rising and peaking, but the association was lost in the older age group with declining infection levels.

We here describe a completely different mechanism of immune modulation where host lipoproteins serve as transporters of schistosome antigens.

Like many schistosome proteins, these antigens are glycosylated with schistosome specific glycoproteins.

As a result of transfer of schistosome antigens to host lipoproteins, circulating antibodies against schistosome antigens will indirectly bind to these lipoproteins.

We have demonstrated the presence of IgG on low-density lipoprotein particles from serum from infected individuals, whereas no antibodies were found on lipoproteins of healthy controls.

Subsequently, these antibody-opsonised lipoproteins are phagocytosed by immune cells carrying an Fc-receptor. Indeed, accumulation of lipids within several types of blood derived immune cells occurred in infected individuals only.

In vitro, this lipid accumulation was associated with apoptosis and reduced viability of neutrophils. The consequences of these lipoprotein binding antibodies for immune cells and for the anti-helminth host response will be discussed.

S79 Eosinophil degranulation against adult Onchocerca ochengi during macrofilaricidal chemotherapy is dependent on depletion of Wolbachia Rowena D.

Hansen1, Germanus S. Bah2, Udo Hetzel1, Vincent N. Tanya2, Alexander J. The basis of the symbiotic relationship between filariae and their Wolbachia endosymbionts is thought to be metabolic, but a role for Wolbachia in defence against immune attack has received little attention.

Neutrophils are attracted to Wolbachia but they are replaced by eosinophils following antibiotic chemotherapy, which degranulate on the worm cuticle.

However, it is not clear whether the eosinophils are involved in killing the filariae or if they are attracted secondarily to dying worms.

In this study, cattle infected with O. In contrast to oxytetracycline, melarsomine had no significant effect on the viability of Wolbachia.

Eosinophil infiltration and degranulation increased significantly only in the oxytetracycline group; whereas nodular gene expression of the chemokine interleukin-8 was lowest in this group.

Moreover, in the early time-points, intense eosinophil degranulation was associated with worm vitality, not degeneration.

These data are consistent with a role for eosinophils in antibiotic-mediated killing, and suggest that Wolbachia prevents a local eosinophilia by recruiting neutrophils.

This shapes the way we think about age profiles of infection, distributions of parasites among hosts, and mechanisms regulating parasite populations.

Many large-scale chemotherapy-based programmes are now in place which aim at controlling infection, reducing morbidity, and eliminating infection where deemed possible.

Depending on whether anthelmintics are mass administered or targeted at particular age- or occupational groups, age-infection profiles will be modified; immune responses will be affected; prevalence vs.

Additionally, we need to monitor for changes in drug efficacy and develop novel assays for detection of active infection and exposure as the sensitivity of parasitological indicators decreases, programmes approach transmission breakpoints, and tools are required to ascertain when to stop.

We need to understand how the parasite population biology paradigm is changing if we aim at supporting parasite control efforts effectively.

S81 Porcine parasites in Northern Ireland: incidence, distribution and correlation with management and control strategies J.

Black1, J. Marks1, A. Endoparasitic worms inflict a huge economic burden on pig production through reduced growth, poor feed conversion efficiencies and higher medication costs.

As yet, anthelmintic resistance has not been reported in swine herds in the UK or Ireland. However, benzimidazole and levamisole resistant nematodes have been identified from herds in Germany concurring with the situation in other nematode parasites of sheep and cattle where multi-drug resistance is rife.

The aim of this study is to investigate the prevalence and distribution of helminth parasites in pig units across Northern Ireland N.

Other species identified included: Hyostrongylus rubidis, Oesophagostumum dentatum, Metastrongylus apri, Trichuris suis and Fasciola hepatica.

These findings indicate that despite good husbandry practice, high-levels of worms are commonplace on most pig units in N.

Echinococcus granulosus is a dog tapeworm that causes the zoonotic disease, cystic echinococcosis. Canine echinococcosis appears to have re-emerged in Powys, Wales following a control programme in the s Buishi et al.

The Office of the Chief Veterinary Officer and 60 the Department for Public Health and Health Professions in the Welsh Assembly Government jointly funded a pilot dog worming campaign as a preventative public health measure.

To evaluate the impact and efficiency of a short-term supervised dog dosing scheme, collection of faecal samples on farm visits and worming of dogs with praziquantel commenced in South Powys in May In Year 1, approximately canid faecal samples were collected from registered farms and delivered to the University of Salford to be tested.

In total faecal samples were tested by coproELISA, of these samples were collected at baseline and were found to have a coproantigen prevalence of A total of samples tested after 3 treatments gave a coproantigen prevalence of 0.

The study will continue to compare the coproantigen prevalence over one year after cessation of dosing. Nicotinic acetylcholine receptors nAChRs are significant drug targets for parasitic nematodes, and several sub-types of these receptors are present on body wall muscle.

We recently identified a novel nAChR subunit gene, acr, from Ascaris suum. A survey of parasitic nematodes, using a combination of sequence data and primary material, demonstrates that acr is conserved in several parasitic species from clades III and V, including Brugia malayi, Haemonchus contortus and Dirofilaria immitis.

To date however, no evidence has been found of acr in any free-living or plant parasitic nematode. A specific antibody against the Asu-ACR subunit was produced; immunocytochemistry on native tissue showed that the subunit was expressed in the head muscle of A.

Sequence similarities with other nAChRs and computer modelling predicted that ACR was capable of forming a homomeric channel.

In vitro expression of ACR in the Xenopus oocyte expression system confirmed this prediction and showed that the receptor responded to both acetylcholine and nicotine, but was not sensitive to levamisole.

The pharmacology and function of this new receptor are being investigated further. S84 Vaccination of rats against fasciolosis by a multivalent vaccine of stage-specific cathepsin proteases induces significant protection Ramamoorthi Jayaraj1, David Piedrafita2, Kemperley Dynon2, Rudi Grams3, Terry W.

Fasciola hepatica produces cathepsin B and cathepsin L in their excretory-secretory material. These proteases are proposed to be key virulence factors for parasite infection and are targets for vaccination.

Cathepsin B isoforms are predominantly released in the juvenile life cycle stage while different cathepsin L isoforms are released throughout the cycle.

Three proteases cathepsin L5, cathepsin L1g and cathepsin B1 were expressed using cDNAs isolated from adult, metacercariae and juvenile flukes, respectively.

Each was used singly or in combination to vaccinate rats that were challenged with F. All vaccinated groups yielded significantly fewer and smaller flukes than the control group, suggesting vaccination retarded liver fluke development.

Kimber, Chuanzhe Song, Jack M. Gallup, Tim A. Bartholomay Departments of Biomedical Sciences and Entomology, Iowa State University, Ames, IA USA Diseases caused by parasitic nematodes perpetuate socioeconomic instability in developing countries by inflicting crippling morbidity and significant mortality.

One reason for the persistence of these diseases is an inadequate portfolio of effective drugs; new, more effective compounds are needed.

A major obstacle to their development is the lack of available tools to validate potential novel drug targets in parasitic nematodes.

RNA Interference RNAi is a tool that allows researchers to suppress genes of interest in experimental organisms or tissues and has become standard for target validation in drug development but a reliable and reproducible protocol for parasitic nematodes has yet to be established.

Here we describe an innovative RNAi strategy to study gene function and validate drug targets in parasitic nematodes.

Our approach uses the filarial nematode Brugia malayi as a model and targets developmental stages of this parasite whilst still in the mosquito host.

We can profoundly suppress expression of a cathepsin-L-like gene using both short interfering RNA and long double stranded RNA injected directly into infected mosquitoes.

Cathepsin L-like suppression elicits aberrant worm phenotypes with motility defects and reduced transmission potential.

Finally we present evidence that other genes are susceptible to this approach. Since completion of the Caenorhabditis elegans genome sequence the generation of genomic and transcriptomic datasets for nematode parasites has evolved relatively slowly.

More recent advances in power sequencing have fuelled a significant expansion in transcriptomic datasets and publication of the first genome sequences for nematode parasites.

An additional stimulus has been the discovery of RNA interference RNAi and its potential to allow gene function or, drug target validation studies in organisms previously refractory to reverse genetic manipulation.

Aiming to decipher the functional context of these sequence data, parasitologists have attempted to adapt RNAi for use in parasitic nematodes.

While progress has been significant in plant parasites, gene silencing in animal-parasitic nematodes has floundered under the difficulties associated with triggering robust transcript knockdown.

To test this we used 77 C. Although preliminary screens indicate that most proteins are reasonably well conserved, notable omissions include proteins responsible for RNAi uptake and spreading.

Warnock, N. Marks, A. RNA interference RNAi provides a reverse genetics platform which facilitates investigations into gene function, providing opportunities for drug target identification and validation.

However, despite initially encouraging results from the scientific community working on animal parasitic nematodes APNs , recent experimentation has revealed that the RNAi response is not robust across all APN species.

Our approach includes the examination of 9 gene transcript targets whose selection was based on transcript abundance, localisation neuronal, gut, reproductive or global tissue expression and previous success in other APN-RNAi experiments.

DsRNAs were delivered to the infective stage of A. Our results indicate variable susceptibility of the targets; no trend was observed between transcript abundance or localisation and susceptibility.

In parasitic nematodes RNAi has proven to be less effective. We have carried out a detailed RNAi study in the sheep gastrointestinal nematode Haemonchus contortus to examine why some genes seem to be more susceptible to RNAi silencing than other genes.

We have obtained specific and reproducible silencing for several genes including the H. Silencing of H11 transcript can be achieved following soaking of L3 infective stage larvae in dsRNA for 24 hours.

Larvae are viable after this treatment with no detrimental effects observed in vitro. To examine any in vivo effects of H11 silencing, sheep were infected with larvae pre-treated with dsRNA to H11 or to a control C.

This is the first demonstration of an in vivo effect following gene silencing in an animal parasitic nematode. This study reveals that putative Meloidogyne incognita orthologues of Caenorhabditis elegans cillial motor proteins, Mi-che-3 and Mi-osm-3, perform functionally comparable roles in the amphids, the main nematode chemosensory organs.

We demonstrate that transcript knockdown by RNAi can recapitulate the aberrant response to chemotactic gradients characteristic of the respective C.

Our sensory assays indicate that knockdown of either transcript using short interfering si RNAs, inhibits the normal attraction and repulsion responses of M.

In addition, we find that the neuropeptide encoding Mi-flp, which is involved in the social feeding phenotype of C. This work demonstrates that RNAi can recapitulate null-phenotypes of functionally conserved amphid proteins in the root knot nematode M.

Cameron, A. Mousley, N. With control relying heavy on triclabendazole, resistance is well established and highlights the need for novel control options.

Within the genus Fasciola there are at least eighteen sub-types of FheCL which show remarkable sequence conservation.

Structural and bioinformatic studies along with the identification of enzyme specificity have allowed the division of multiple cathepsin Ls into sub-categories designated clades; these appear to have distinct functional roles.

Promiscuous siRNAs have been designed to silence multiple clades simultaneously, whereas the selective siRNAs are clade specific.

In addition to qPCR, the impact of silencing on phenotype has been examined. The preliminary data highlight variation in silencing susceptibilities and efficiencies and demonstrate the need to optimize individual siRNAs prior to functional assessments.

Stevenson1, J. Dalzell1, C. Until recently, carbamate and organophosphate-based nematicides have been used to control plant parasitic nematodes, but have been withdrawn due to environmental concerns.

In an effort to investigate if the RNAi-susceptibility of potato cyst nematode gene transcripts is tissuedependent, we set out to knockdown G.

Initially, genes expressed exclusively in neuronal cells of the head ganglia Gp-ace-2 encoding acetylcholinesterase or in the subventral oesophageal gland cells Gp-cell-1 and Gpcm-1 encoding B-1, 4 endoglucanase [cellulase] and chorismate mutase, respectively.

The end goal will be to breed plants expressing nematode-specific dsRNA or siRNAs in planta which will be resistant to parasitic nematode infestation.

Our aim is to assess whether ivermectin sensitivity in this strain can be restored by expressing GluCl subunit cDNA from Haemonchus contortus, a parasitic 64 nematode from the same clade as C.

We have used particle bombardment to create transgenic C. Dose response curves for ivermectin were comparable between the Hco-avrB strain and an avr; glc-1 mutant, indicating that the H.

In contrast, the triple mutant containing Hco-avrA cDNA did not show any rescue of ivermectin sensitivity Our data using C.

Furthermore, we show that C. Marks1, Michael J. Kimber2, Tim A. Day2, Betty A. Eipper3, Richard E. In vertebrates, PHM and PAL are expressed as separate domains of the bifunctional protein peptidylglycine alpha-amidating monooxygenase PAM , while a number of invertebrates display various different arrangements of monofunctional enzymes.

In situ hybridization demonstrated that in adult schistosomes, SmPAL mRNA Sm-pal-1 is expressed in the central nervous system, consistent with its role in the amidation of neuropeptides in S.

Heterologous expression showed that SmPAL is a catalytically active, efficiently secreted amidating enzyme, with functional characteristics analogous to other eukaryotic amidating enzymes.

Nevertheless, the fundamental role of SmPAL in neuropeptide maturation, and structural differences from the host enzyme, make it appealing as a drug target candidate.

Kimber2, Nikki J. Marks1, Tim A. Published studies in S. Here we aimed to investigate whether RNAi could be triggered in deeper tissues, by performing a small-scale RNAi screen of six neurone-specific gene transcripts identified from the S.

Using electroporation-mediated delivery of bp dsRNA to in-vitro schistosomules, and assaying subsequent transcript knockdown by semi-quantitative real-time PCR, we achieved specific transcript knockdown with all of our targets, although the degree of knockdown varied markedly between genes.

Although these experiments are ongoing, our conclusion at this stage is that our target genes are refractory to phenotypic analysis, due either to functional redundancy, or insufficient ablation of transcript level.

Short amidated neuropeptides, FMRFamide-like peptides FLPs , are distributed abundantly throughout the nervous system of every flatworm examined and they produce potent myoexcitation.

Our goal here was to determine the mechanism by which FLPs elicit contractions of schistosome muscle fibers.

Now working at Anhui Institute of Parasitic Diseases Schistosoma japonicum remains highly endemic in China and has recently re-emerged in previously controlled regions.

To investigate the potential role for any animals other than humans and bovines in the transmission, longitudinal investigation of S.

The highest prevalence and infection intensity were observed in rodents in the hilly region and in the cattle in the marshland.

A late afternoon shedding pattern was observed in the hilly and a morning-afternoon dual shedding pattern within the marshland.

Characterisation of the parasite population genetic diversity also indicated cattle to be the main definitive host reservoir species in the marshland, which was further confirmed by sibling relationship analyses.

In the hilly region, however, in addition to the role of rodents as the main reservoirs to maintain the disease, dogs, with their higher mobility, may also play a significant role in S.

The implications of these results, in terms of parasite strain sub-structuring and targeted disease control, were discussed.

Deberiotstraat 32, B Leuven, Belgium. Schistosome flukes cause significant disease in humans and ruminants in tropical and sub-tropical regions.

The two host-life cycle with a sexual stage within the mammalian host facilitates inter species interactions.

Hybridization between schistosome species can occur but in most cases host specificity and ecology are thought to maintain species barriers.

Here we report on the emergence of new hybrid strains of schistosomes found in Senegalese children and cattle resulting from introgressive hybridization between ruminant and human parasites.

This situation has arisen due to the increasing close contact of livestock and people potentially brought about by water development projects and the spread of appropriate intermediate snail hosts.

Our findings have come to light due to optimized sampling and genotyping techniques of individual schistosome larval stages enabling multi loci molecular analyses of parasites directly from the field.

Gene exchange following hybridization can lead to phenotypic innovations that can ultimately lead to changes in disease epidemiology.

Understanding the biology and interactions of these dioecious parasites is essential for developing strategies for schistosomiasis control in West Africa.

Emphasis has been given to the existence of a strong regulatory network in response to high and prolonged exposure to helminth parasites.

We investigated the influence of. The prevalence of atopic reactions was Furthermore, there was a significant negative correlation between infection intensity and the allergen specific IgE.

These results indicate that skin sensitivity to common aeroallergens may be suppressed in S. Interestingly, no correlation was observed between the skin prick results and the allergen-specific IgE suggesting that regulation might occur at the effector interface of immune responses.

A vaccine against schistosomiasis remains an unfulfilled goal. A concept we are investigating is to target immune responses at poorly immunogenic molecules during normal infection.

Antibodies which neutralize this enzyme might abort the infection at an early stage and our hypothesis is that such antibodies may be induced if Sm-CE is in an inactivated, but properly-folded form.

We are currently trying to express the His-tagged recombinant protein in a correct native secondary structure. Attempts will be made to inactivate the enzymatic activity of the rSm-CE-Fc by site-directed mutagenesis of the active site serine S Experiments are underway to test whether either of the recombinant products, rSmCE-His and rSm-CE-Fc, induce protective immunity against schistosome challenge in mice.

S Development and validation of a quantitative, high-throughput, fluorescent-based bioassay to detect Schistosoma viability E. Peak, I.

Human schistosomiasis is currently reliant on the use of one drug Praziquantal for its global control.

Resistance to this drug has the potential to remove our ability to treat this neglected tropical disease and so lends urgency to the search for novel drugs and drug targets.

Current methods for detecting schistosome viability rely on qualitative microscopic criteria, which require an understanding of parasite morphology, and most importantly, can be subjectively interpreted.

These methods are unsuitable for high-throughput functional genomics- or drug based- screens currently required by the schistosome community to accelerate discovery of novel chemotherapeutics.

Here we present a quantitative microtiter-based method for objectively detecting schistosomula viability that takes advantage of the differential uptake of fluorophores by living organisms.

2 thoughts on “Anabel MГ¶bius

  1. Ich denke, dass Sie nicht recht sind. Geben Sie wir werden besprechen. Schreiben Sie mir in PM, wir werden reden.

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