Understanding the spatio-temporal dynamics of meningitis epidemics outside the belt: the case of the Democratic Republic of Congo (DRC).

BACKGROUND: Bacterial meningitis remains a major threat for the population of the meningitis belt. Between 2004 and 2009, in the countries of this belt, more than 200,000 people were infected with a 10% mortality rate. However, for almost 20 years, important meningitis epidemics are also reported outside this belt. Research is still very poorly developed in this part of the word like in the Democratic Republic of Congo (DRC), which experiences recurrent epidemics. This article describes for the first time the spatio-temporal patterns of meningitis cases and epidemics in DRC, in order to provide new insights for surveillance and control measures. METHODS: Based on weekly suspected cases of meningitis (2000-2012), we used time-series analyses to explore the spatio-temporal dynamics of the disease. We also used both geographic information systems and geostatistics to identify spatial clusters of cases. Both using conventional statistics and the Cleveland's algorithm for decomposition into general trend, seasonal and residuals, we searched for the existence of seasonality. RESULTS: We observed a low rate of biological confirmation of cases (11%) using soluble antigens search, culture and PCR. The main strains found are Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis (A and C) serogroups. We identified 8 distinct spatial clusters, located in the northeastern and southeastern part of DRC, and in the capital city province, Kinshasa. A low seasonal trend was observed with higher incidence and attack rate of meningitis during the dry season, with a high heterogeneity in seasonal patterns occurring across the different districts and regions of DRC. CONCLUSION: Despite challenges related to completeness of data reporting, meningitis dynamics shows weak seasonality in DRC. This tends to suggest that climatic, environmental factors might be less preponderant in shaping seasonal patterns in central Africa. The characterization of 8 distinct clusters of meningitis could be used for a better sentinel meningitis surveillance and optimization of vaccine strategy in DRC. Improving biological monitoring of suspected cases should be a priority for future eco-epidemiological studies to better understand the emergence and spread of meningitis pathogens, and the potential ecological, environmental drivers of this disease.

How Do Richness and Composition of Diet Shape Trace Metal Exposure in a Free-Living Generalist Rodent, Apodemus sylvaticus.

Exposure of terrestrial mammals to chemical contaminants like trace metals (TMs) is considered to be mainly based on trophic transfer. Although relationships between TM transfer to animals and identity of contaminated food have been studied, the variation of the TM transfer with respect to diet diversity has been poorly documented. In this study, the oral exposure to TMs of wood mice Apodemus sylvaticus was investigated with respect to both the number of different items, i.e., diet richness, and the identity of items determined by metabarcoding from their stomach content, i.e., diet composition. The results showed that consuming Salicaceae, a known cadmium accumulator plant family, significantly increased exposure to cadmium and zinc. However, an increase in diet richness minimized exposure to cadmium when mice consumed Salicaceae items. This strongly suggests that TM accumulator items can lead to a high oral exposure to TMs but that such high exposure due to TM accumulator items can be " diluted" by diet richness due to other low accumulator items. Our results clearly indicate that both the presence of certain items in the diet and diet richness are important determinants of exposure to TMs in generalist animals, which matches the predictions of the " diet dilution hypothesis".

Does pollution influence small mammal diet in the field? A metabarcoding approach in a generalist consumer.

Mammals are mainly exposed to trace metals (TMs) via consuming contaminated food. Several studies have demonstrated relationships between metal concentrations in food and in animal tissues. However, potential effects of TMs on feeding behaviour of wildlife have been poorly documented under field conditions, despite experimental evidence showing that food selection is impacted by resource contamination. Here, we test the hypothesis that the diet of a generalist rodent, the wood mouse (Apodemus sylvaticus), is altered by soil TM contamination in the field. Wood mice were sampled in spring and in autumn along a gradient of soil contamination in the surroundings of a former smelter located in northern France. Available resources in the field were inventoried, and the diet of the animals was analysed using DNA "metabarcoding." We demonstrated that (a) relationship between the resource richness in the diet and their richness in the field was altered by soil metal contamination. Wood mice specialized their diet along the gradient of soil metal contamination for both plant and invertebrate resources in spring. We also showed that (b) preference for Salicaceae, a plant family accumulating metals, decreased when soil contamination increased. These results suggest that environmental TM pollution could act as a force modulating trophic interactions in terrestrial food webs, thereby affecting wildlife exposure to contaminants by trophic route.

The adaptation of generalist predators' diet in a multi-prey context: insights from new functional responses.

The ability for a generalist consumer to adapt its foraging strategy (the multi-species functional response, MSFR) is a milestone in ecology as it contributes to the structure of food webs. The trophic interaction between a generalist predator, as the red fox or the barn owl, and its prey community, mainly composed of small mammals, has been empirically and theoretically widely studied. However, the extent to which these predators adapt their diet according to both multi-annual changes in multiple prey species availability (frequency dependence) and the variation of the total prey density (density dependence) is unexplored.We provide a new general model of MSFR disentangling changes in prey preference according to variation of prey frequency (switching) and of total prey density (we propose the new concept of "rank switching"). We apply these models to two large data sets of red fox and barn owl foraging. We show that both frequency-dependent and density-dependent switching are critical properties of these two systems, suggesting that barn owl and red fox have an accurate image of the prey community in terms of frequency and absolute density. Moreover, we show that negative switching, which can lead to prey instability, is a strong property of the two systems.

Competence of hosts and complex foraging behavior are two cornerstones in the dynamics of trophically transmitted parasites.

Multi-host trophically transmitted parasite (TTP) is a common life cycle where prey and predators are respectively intermediate and definitive hosts of the parasite. In these systems, the foraging response of the predator toward variations in prey community composition underlies the dynamic of the parasite. Therefore, modeling epidemiological dynamic of infectious diseases considering ecological predator-prey interactions is essential to understand the spreading of parasites in ecosystems. However, two important weaknesses of previous TTP models including feeding interaction can be pointed out: (i) the choice of a linear density-dependent contact rate is faintly realistic as it supposes an unlimited ingestion rate with an increase of prey density and (ii) considering only one host prey species prevents the study of host biodiversity effect due to change in the prey community composition where species have different competences to be infected and to transmit the parasite. This article attempts to address the dynamics of parasite in a context of multiple intermediate hosts differentiated by their competences and of complex foraging behavior of the predator. We present and analyze a deterministic one predator-two prey model, which is then used to explore the transmission cycle of the cestode Echinococcus multilocularis. This study examines the foraging condition for the co-existence of the prey, and then, based on the computation of the threshold measure of disease risk, R0, we show that the pattern of feeding interactions changes the relationship between disease risk and prey community composition. Finally, we disentangle the mechanism leading to the counter-intuitive observation of a decrease of disease risk while the population density of intermediate hosts increases.

Retrospective analyses of fox feces by real-time PCR to identify new endemic areas of Echinococcus multilocularis in France.

Alveolar echinococcosis is considered to be the most serious zoonosis in the Northern Hemisphere's cold or temperate regions. In Europe, the parasite has a sylvatic life cycle based on predator-prey interactions, mainly between red foxes and small rodents. Echinococcus multilocularis has been observed to have spread across Europe over the last three decades. In France, a westward spread of the parasite's known endemic areas has been described. In this study, a retrospective analysis of fox feces by real-time PCR was carried out in four départements not previously investigated and considered free along with two endemic control departments. The fox feces collected from 2000 to 2004 were analyzed by real-time PCR. Fecal prevalence in the two endemic departments of Doubs and Côte d'Or were estimated at 12 % [6.4-20.0 %] and 4.2 % [1.1-10.3 %], respectively. No positive samples were identified among the 72 feces collected in Drôme or the 112 from Allier, which is consistent with the very low expected prevalence should the parasite be present. Three positive samples were recovered in the Seine-Maritime and Hautes-Alpes départements, resulting in a prevalence of 3.5 % [0.7-10.0 %] and 2.5 % [0.5-7.1 %], respectively. From now on, Hautes-Alpes constitutes the new southern border of the endemic areas in France and confirms the southward expansion previously highlighted. Real-time copro-PCR proved useful in identifying new endemic areas even with low prevalence. Due to the spread of E. multilocularis in France and associated zoonotic risk, it is necessary to expand surveillance in order to fully define all the country's endemic areas. On a continental scale, the development and harmonization of surveillance programs are now needed in order to obtain a global overview of the presence of E. multilocularis and to tailor potential countermeasures.

Assessing the role of individual foxes in environmental contamination with Echinococcus multilocularis through faecal samples.

Key parasite transmission parameters are difficult to obtain from elusive wild animals. For Echinococcus multilocularis, the causative agent of alveolar echinococcosis (AE), the red fox is responsible for most of the environmental contamination in Europe. The identification of individual spreaders of E. multilocularis environmental contamination is crucial to improving our understanding of the ecology of parasite transmission in areas of high endemicity and optimising the effectiveness of prevention and control measures in the field. Genetic faecal sampling appears to be a feasible method to gain information about the faecal deposition of individual animals. We conducted a 4 year faecal sampling study in a village that is highly endemic for E. multilocularis, to assess the feasibility of individual identification and sexing of foxes to describe individual infection patterns. Individual fox identification from faecal samples was performed by obtaining reliable genotypes from 14 microsatellites and one sex locus, coupled with the detection of E. multilocularis DNA, first using captive foxes and then by environmental sampling. From a collection of 386 fox stools collected between 2017 and 2020, tested for the presence of E. multilocularis DNA, 180 were selected and 124 samples were successfully genotyped (68.9%). In total, 45 unique individual foxes were identified and 26 associated with at least one sample which tested positive for E. multilocularis (Em(+)). Estimation of the population size showed the fox population to be between 29 and 34 individuals for a given year and 67 individuals over 4 years. One-third of infected individuals (9/26 Em(+) foxes) deposited 2/3 of the faeces which tested positive for E. multilocularis (36/60 Em(+) stools). Genetic investigation showed a significantly higher average number of multiple stools for females than males, suggesting that the two sexes potentially defecated unequally in the studied area. Three partially overlapping clusters of fox faeces were found, with one cluster concentrating 2/3 of the total E. multilocularis-positive faeces. Based on these findings, we estimated that 12.5 million E. multilocularis eggs were produced during the study period, emphasizing the high contamination level of the environment and the risk of exposure faced by the parasite hosts.

Detecting nested clusters of human alveolar echinococcosis.

Recent changes in the epidemiology of alveolar echinococcosis (AE) in Eurasia have led to increasing concerns about the risk of human AE and the need for a thorough evaluation of the epidemiological situation. The aim of this study was to explore the use of a National Register to detect complex distribution patterns on several scales. The data were human AE cases from the FrancEchino register, diagnosed in France from 1982 to 2011. We used the Kulldorff spatial scan analysis to detect non-random locations of cases. We proposed an exploratory method that was based on the successive detection of nested clusters inside each of the statistically significant larger clusters. This method revealed at least 4 levels of disease clusters during the study period. The spatial variations of cluster location over time were also shown. We conclude that National Human AE registers, although not exempted from epidemiological biases, are currently the best way to achieve an accurate representation of human AE distribution on various scales. Finally, we confirm the multi-scale clustered distribution of human AE, and we hypothesize that our study may be a reasonable starting point from which to conduct additional research and explore the processes that underlie such distributions.

Transmission ecosystems of Echinococcus multilocularis in China and Central Asia.

From continental to regional scales, the zoonosis alveolar echinococcosis (AE) (caused by Echinococcus multilocularis) forms discrete patches of endemicity within which transmission hotspots of much larger prevalence may occur. Since the late 80s, a number of hotspots have been identified in continental Asia, mostly in China, wherein the ecology of intermediate host communities has been described. This is the case in south Gansu, at the eastern border of the Tibetan plateau, in south Ningxia, in the western Tian Shan of Xinjiang, and in the Alay valley of south Kyrgyzstan. Here we present a comparative natural history and characteristics of transmission ecosystems or ecoscapes. On this basis, regional types of transmission and their ecological characteristics have been proposed in a general framework. Combining climatic, land cover and intermediate host species distribution data, we identified and mapped 4 spatially distinct types of transmission ecosystems typified by the presence of one of the following small mammal 'flagship' species: Ellobius tancrei, Ochotona curzoniae, Lasiopodomys brandtii or Eospalax fontanierii. Each transmission ecosystem had its own characteristics which can serve as a reference for further in-depth research in the transmission ecology of E. multilocularis. This approach may be used at fine spatial scales to characterize other poorly known transmission systems of the large Eurasian endemic zone, and help in consideration of surveillance systems and interventions.

Detection of human taeniases in Tibetan endemic areas, China.

Detection of taeniasis carriers of Taenia solium is essential for control of cysticercosis in humans and pigs. In the current study, we assessed the positive detection rate of a self-detection tool, stool microscopy with direct smear and coproPCR for taeniasis carriers in endemic Tibetan areas of northwest Sichuan. The self-detection tool through questioning about a history of proglottid expulsion within the previous one year showed an overall positive detection rate of more than 80% for Taenia saginata, T. solium and T. asiatica. The positive detection rate was similar for T. saginata and T. solium. In 132 taeniid tapeworm carriers, 68 (51·5%) were detected by microscopy and 92 (69·7%) were diagnosed by coproPCR. A combination of microscopy and coproPCR increased the positive detection rate to 77·3%. There remained 10 cases (7·6%) coproPCR negative but microscopy positive. Due to the high cost and complicated process, coproPCR is required for the identification of Taenia species only when necessary, though it had a significant higher positive detection rate than microscopy. Combined use of self-detection and stool microscopy are recommended in community-based mass screening for taeniases in this Tibetan area or in other situation-similar endemic regions.

Advances in diagnosis and spatial analysis of cysticercosis and taeniasis.

Human cysticercosis, caused by accidental ingestion of eggs of Taenia solium, is one of the most pathogenic helminthiases and is listed among the 17 WHO Neglected Tropical Diseases. Controlling the life-cycle of T. solium between humans and pigs is essential for eradication of cysticercosis. One difficulty for the accurate detection and identification of T. solium species is the possible co-existence of two other human Taenia tapeworms (T. saginata and T. asiatica, which do not cause cysticercosis in humans). Several key issues for taeniasis/cysticercosis (T/C) evidence-based epidemiology and control are reviewed: (1) advances in immunological and molecular tools for screening of human and animals hosts and identification of Taenia species, with a focus on real-time detection of taeniasis carriers and infected animals in field community screenings, and (2) spatial ecological approaches that have been used to detect geospatial patterns of case distributions and to monitor pig activity and behaviour. Most recent eco-epidemiological studies undertaken in Sichuan province, China, are introduced and reviewed.

Effects of chronic exposure to toxic metals on haematological parameters in free-ranging small mammals.

Blood circulates through the vascular system to carry oxygen, nutrients and metabolites to and away from tissues, and as such is a key-component of animal physiology. The impacts of metal pollution on blood, however, are poorly documented in free-ranging vertebrates. While the counteracting effect of selenium on mercury toxicity is well known in marine mammals, its potential role against the toxicity of other metals is less studied, especially on terrestrial wildlife. We explored the consequences of chronic exposure to two non-essential metals (cadmium and lead) along a pollution gradient in Northern France, on eleven haematological parameters in two free ranging small mammals, the wood mouse Apodemus sylvaticus and the bank vole Myodes glareolus. We hypothesized that haematology was related to metal concentrations in tissues, and that selenium might exert modulating effects. Concentrations of cadmium and lead in the tissues indicated an increased chronic exposure to and accumulation of metals along the gradient. Some haematological parameters were not explained by any measured variables while some others varied only with gender or age. Red blood cells, red blood cells distribution width, and blood iron concentration, however, decreased with increasing cadmium in the tissues in wood mice. Red blood cells and haemoglobin decreased with increasing renal lead and hepatic cadmium, respectively, in bank voles. Red blood cells distribution width in wood mice increased with cadmium concentrations in the liver but this was counteracted by high selenium levels in the same organ. An interaction of selenium and lead on red blood cells was also observed in bank voles. Further, selenium concentrations were associated with an increase of monocytes in wood mice. The present results show that toxic metals were related to haematology changes, particularly erythrocyte indicators, and that some essential elements like selenium should be measured as well since they may counteract toxic effects.

Mapping small mammal optimal habitats using satellite-derived proxy variables and species distribution models.

Small mammal species play an important role influencing vegetation primary productivity and plant species composition, seed dispersal, soil structure, and as predator and/or prey species. Species which experience population dynamics cycles can, at high population phases, heavily impact agricultural sectors and promote rodent-borne disease transmission. To better understand the drivers behind small mammal distributions and abundances, and how these differ for individual species, it is necessary to characterise landscape variables important for the life cycles of the species in question. In this study, a suite of Earth observation derived metrics quantifying landscape characteristics and dynamics, and in-situ small mammal trapline and transect survey data, are used to generate random forest species distribution models for nine small mammal species for study sites in Narati, China and Sary Mogul, Kyrgyzstan. These species distribution models identify the important landscape proxy variables driving species abundance and distributions, in turn identifying the optimal conditions for each species. The observed relationships differed between species, with the number of landscape proxy variables identified as important for each species ranging from 3 for Microtus gregalis at Sary Mogul, to 26 for Ellobius tancrei at Narati. Results indicate that grasslands were predicted to hold higher abundances of Microtus obscurus, E. tancrei and Marmota baibacina, forest areas hold higher abundances of Myodes centralis and Sorex asper, with mixed forest-grassland boundary areas and areas close to watercourses predicted to hold higher abundances of Apodemus uralensis and Sicista tianshanica. Localised variability in vegetation and wetness conditions, as well as presence of certain habitat types, are also shown to influence these small mammal species abundances. Predictive application of the Random Forest (RF) models identified spatial hot-spots of high abundance, with model validation producing R2 values between 0.670 for M. gregalis transect data at Sary Mogul to 0.939 for E. tancrei transect data at Narati. This enhances previous work whereby optimal habitat was defined simply as presence of a given land cover type, and instead defines optimal habitat via a combination of important landscape dynamic variables, moving from a human-defined to species-defined perspective of optimal habitat. The species distribution models demonstrate differing distributions and abundances of host species across the study areas, utilising the strengths of Earth observation data to improve our understanding of landscape and ecological linkages to small mammal distributions and abundances.

Environmental pollution and nutritional quality modulate immune response of the wood mouse (Apodemus sylvaticus) through hormonal disturbances.

Cadmium (Cd) and lead (Pb) are known to enhance immune cell damages and to decrease cellular immunity, promoting higher susceptibility to infectious diseases. Selenium (Se) is an essential element involved in immunity and reactive oxygen species scavenging. This study aimed at evaluating how Cd and Pb and low nutritional (Se) quality modulate immune response to a bacterial lipopolysaccharide (LPS) challenge in wood mice (Apodemus sylvaticus). Mice were trapped near a former smelter in northern France in sites of High or Low contamination. Individuals were challenged immediately after capture or after five days of captivity, fed a standard or a Se-deficient diet. Immune response was measured with leukocyte count and plasma concentration of TNF-α, a pro-inflammatory cytokine. Faecal and plasma corticosterone (CORT), a stress-hormone involved in anti-inflammatory processes, was measured to assess potential endocrine mechanisms. Higher hepatic Se and lower faecal CORT were measured in free-ranging wood mice from High site. LPS-challenged individuals from High site showed steeper decrease of circulating leukocytes of all types, higher TNF-α concentrations, and a significant increase of CORT, compared to individuals from Low site. Challenged captive animals fed standard food exhibited similar patterns (decrease of leukocytes, increase of CORT, and detectable levels of TNF-α), with individuals from lowly contaminated site having higher immune responses than their counterparts from highly polluted site. Animals fed Se-deficient food exhibited lymphocytes decrease, no CORT variation, and average levels of TNF-α. These results suggest (i) a higher inflammatory response to immune challenge in free-ranging animals highly exposed to Cd and Pb, (ii) a faster recovery of inflammatory response in animals lowly exposed to pollution when fed standard food than more exposed individuals, and (iii) a functional role of Se in the inflammatory response. The role of Se and mechanisms underlying the relationship between glucocorticoid and cytokine remain to be elucidated.

Westward spread of Echinococcus multilocularis in foxes, France, 2005-2010.

During 2005-2010, we investigated Echinococcus multilocularis infection within fox populations in a large area in France. The parasite is much more widely distributed than hitherto thought, spreading west, with a much higher prevalence than previously reported. The parasite also is present in the large conurbation of Paris.

Vegetation shapes aboveground invertebrate communities more than soil properties and pollution: a preliminary investigation on a metal-contaminated site.

Pollution with trace metals (TM) has been shown to affect diversity and/or composition of plant and animal communities. While ecotoxicological studies have estimated the impact of TM contamination on plant and animal communities separately, ecological studies have widely demonstrated that vegetation is an important factor shaping invertebrate communities. It is supposed that changes in invertebrate communities under TM contamination would be explained by both direct impact of TM on invertebrate organisms and indirect effects due to changes in plant communities. However, no study has clearly investigated which would more importantly shape invertebrate communities under TM contamination. Here, we hypothesized that invertebrate communities under TM contamination would be affected more importantly by plant communities which constitute their habitat and/or food than by direct impact of TM. Our analysis showed that diversity and community identity of flying invertebrates were explained only by plant diversity which was not affected by TM contamination. Diversity of ground-dwelling (GD) invertebrates in spring was explained more importantly by plant diversity (27% of variation) than by soil characteristics including TM concentrations (8%), whereas their community identity was evenly explained by plant diversity and soil characteristics (2-7%). In autumn, diversity of GD invertebrates was only explained by plant diversity (12%), and their identity was only explained by soil characteristics (8%). We conclude that vegetation shapes invertebrate communities more importantly than direct effects of TM on invertebrates. Vegetation should be taken into account when addressing the impacts of environmental contamination on animal communities.

Pervasive exposure of wild small mammals to legacy and currently used pesticide mixtures in arable landscapes.

Knowledge gaps regarding the potential role of pesticides in the loss of agricultural biodiversity worldwide and mixture-related issues hamper proper risk assessment of unintentional impacts of pesticides, rendering essential the monitoring of wildlife exposure to these compounds. Free-ranging mammal exposure to legacy (Banned and Restricted: BRPs) and currently used (CUPs) pesticides was investigated, testing the hypotheses of: (1) a background bioaccumulation for BRPs whereas a "hot-spot" pattern for CUPs, (2) different contamination profiles between carnivores and granivores/omnivores, and (3) the role of non-treated areas as refuges towards exposure to CUPs. Apodemus mice (omnivore) and Crocidura shrews (insectivore) were sampled over two French agricultural landscapes (n = 93). The concentrations of 140 parent chemicals and metabolites were screened in hair samples. A total of 112 compounds were detected, showing small mammal exposure to fungicides, herbicides and insecticides with 32 to 65 residues detected per individual (13-26 BRPs and 18-41 CUPs). Detection frequencies exceeded 75% of individuals for 13 BRPs and 25 CUPs. Concentrations above 10 ng/g were quantified for 7 BRPs and 29 CUPs (in 46% and 72% of individuals, respectively), and above 100 ng/g for 10 CUPs (in 22% of individuals). Contamination (number of compounds or concentrations) was overall higher in shrews than rodents and higher in animals captured in hedgerows and cereal crops than in grasslands, but did not differ significantly between conventional and organic farming. A general, ubiquitous contamination by legacy and current pesticides was shown, raising issues about exposure pathways and impacts on ecosystems. We propose a concept referred to as "biowidening", depicting an increase of compound diversity at higher trophic levels. This work suggests that wildlife exposure to pesticide mixtures is a rule rather than an exception, highlighting the need for consideration of the exposome concept and questioning appropriateness of current risk assessment and mitigation processes.

Echinococcus multilocularis genetic diversity in Swiss domestic pigs assessed by EmsB microsatellite analyzes.

Assessing the genetic diversity of the parasite Echinococcus multilocularis provides key information about the temporal and spatial strain flow in a given area. Previous studies indicated that a historical endemic area conventionally presents a relatively high genetic diversity, whereas peripheral or newly endemic areas exhibit a more restricted variability of the parasite. The Swiss plateau region is part of the European historically endemic area, and the genetic diversity has already been investigated by assessing either human metacestode isolates or adult worms from foxes. To date, there have been no studies covering the whole geographical area affected by the parasite. The aim of the present study was to make use of the domestic pig to investigate the genetic diversity of E. multilocularis in relation to spatial distribution. A total of 55 E. multilocularis-induced hepatic lesions from slaughtered pigs from Switzerland were studied using EmsB microsatellite analyzes, and findings were compared to already published data (originating from human, primate, foxes, and rodent samples). A total of 12 EmsB profiles were described among the domestic pigs, some of them presenting a clear spatial organization in the Swiss plateau, with three of the main profiles geographically separated. One of the 12 EmsB profiles has been newly identified for Switzerland in this study, while the other 11 profiles had been previously described in other Swiss E. multilocularis isolates from other hosts. Overall, a total of 18 EmsB profiles have so far been described within the Swiss endemic area. Six profiles appeared only among human, primate, rodent, and fox samples. Based on a richness and diversity accumulation analysis, the sampling efficiency for the whole studied area has now been improved considerably by compilation of 178 E. multilocularis specimens obtained from four different intermediate and one definitive host species in Switzerland.

Predator dietary response to prey density variation and consequences for cestode transmission.

The functional response of predators to prey density variations has previously been investigated in order to understand predation patterns. However, the consequences of functional response on parasite transmission remain largely unexplored. The rodents Microtus arvalis and Arvicola terrestris are the main prey of the red fox Vulpes vulpes in eastern France. These species are intermediate and definitive hosts of the cestode Echinococcus multilocularis. We explored the dietary and contamination responses of the red fox to variations in prey density. The dietary response differed between the two prey species: no response for M. arvalis and a type III-like (sigmoidal) response for A. terrestris that shows possible interference with M. arvalis. The fox contamination response followed a type II shape (asymptotic) for both species. We conclude that fox predation is species specific and E. multilocularis transmission is likely to be regulated by a complex combination of predation and immunologic factors. These results should provide a better understanding of the biological and ecological mechanisms involved in the transmission dynamics of trophically transmitted parasites when multiple hosts are involved. The relevance of the models of parasite transmission should be enhanced if non-linear patterns are taken into account.

Assessment of the exposure to Echinococcus multilocularis associated with carnivore faeces using real-time quantitative PCR and flotation technique assays.

The eggs of Echinococcus multilocularis, the infectious stage, are spread into the environment through wild and domestic carnivore faeces. The spatial location of the faeces containing infective E. multilocularis eggs is a key parameter for studying areas of exposure and understanding the transmission processes to the intermediate hosts and humans. Echinococcus multilocularis faecal prevalence is often assessed by detecting E. multilocularis DNA, not necessarily eggs. This work aimed to determine the percentage of faeces containing E. multilocularis eggs in a rural town and its surroundings and whether this level of precision is relevant in assessing exposure to E. multilocularis. For this purpose, we developed a combined molecular and microscopic approach to investigate the E. multilocularis exposure of potential hosts in the environment from field-collected carnivore faeces. Carnivore defecation patterns were then spatialized to study the spatial distribution of E. multilocularis. Faeces were screened for E. multilocularis DNA using a specific real-time quantitative PCR (qPCR). Echinococcus multilocularis eggs were morphologically identified from E. multilocularis-specific qPCR-positive faeces after sucrose flotation and individually confirmed through specific PCR and sequencing. The spatial distribution of E. multilocularis was studied using Kulldorff statistics. Echinococcus multilocularis eggs were identified mostly in fox faeces positive for E. multilocularis DNA by qPCR (n = 27/70) and only from 1 of 15 copro-samples from dogs and 1 of 5 from cats. The faecal prevalence of E. multilocularis DNA and eggs was overdispersed, with the same geographical patterns. These data suggest that E. multilocularis DNA and/or egg detection in carnivore faeces, mainly that of foxes, is appropriate in ecological studies of E. multilocularis transmission.