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Partie 3 : Douglas-fir ecology; International audience

European Commission FP7 Marie Curie Initial Training Network ‘ParaMet’ [290080 to S.S.]; ANR project MetaboHub [ANR-11-INBS-0010 to B.M.]; Wellcome Trust [085349]; The work of Fiona Achcar was part of the SysMO SilicoTryp project coordinated by R.B. Funding for open access charge: European Commission FP7 Marie Curie Initial Training Network ‘ParaMet’ [290080]. The metabolic network of a cell represents the catabolic and anabolic reactions that interconvert small molecules (metabolites) through the activity of enzymes, transporters and non-catalyzed chemical reactions. Our understanding of individual metabolic networks is increasing as we learn more about the enzymes that are active in particular cells under particular conditions and as technologies advance to allow detailed measurements of the cellular metabolome. Metabolic network databases are of increasing importance in allowing us to contextualise data sets emerging from transcriptomic, proteomic and metabolomic experiments. Here we present a dynamic database, TrypanoCyc (http://www.metexplore.fr/trypanocyc/), which describes the generic and condition-specific metabolic network of Trypanosoma brucei, a parasitic protozoan responsible for human and animal African trypanosomiasis. In addition to enabling navigation through the BioCyc-based TrypanoCyc interface, we have also implemented a network-based representation of the information through MetExplore, yielding a novel environment in which to visualise the metabolism of this important parasite. Publisher PDF

International audience; Zoonoses – infectious diseases communicable between animals and humans –, drug resistance and environmental pollution are now causing serious health problems worldwide. These problems are closely tied to global environmental and socio-economic changes and to the transformation of production systems at the territorial level. In this context, health management is becoming a complex issue: it needs to be addressed in close collaboration with the public veterinary health, agriculture and environment sectors. New uncertainties are emerging, and nonconventional actors are entering the scene alongside the decision-makers traditionally responsible for public health. The participatory modelling and simulation approach incorporates the diverse knowledge of all of these actors. It reveals uncertainties and teaches participants how to manage them, to make decisions and to share responsibility. It constitutes a practical solution to ensure health issues are better integrated into territorial planning policies.; Les zoonoses — maladies infectieuses transmises entre les animaux et l’homme —, les résistances aux médicaments et les pollutions environnementales posent aujourd’hui de graves problèmes de santé publique à l’échelle mondiale. Ces problèmes de santé sont fortement liés aux changements environnementaux et socioéconomiques globaux et aux transformations des systèmes de production à l’échelle des territoires. Dans ce contexte, la gestion de la santé devient complexe : elle doit être abordée en lien étroit avec la santé publique vétérinaire, l’agriculture et l’environnement. De nouvelles incertitudes apparaissent, et des acteurs non conventionnels entrent aux côtés des décideurs classiquement chargés de la santé publique. La démarche de modélisation et de simulation participative intègre les connaissances hétérogènes de tous ces acteurs. Elle révèle les incertitudes et permet ensuite de s’entraîner à les gérer, à prendre des décisions et à partager les responsabilités. Elle constitue une solution pragmatique pour mieux intégrer la santé dans les politiques d’aménagement du territoire.

Les faits de santé peuvent être localisés et leur organisation spatiale détectée grâce aux technologies SIG. De fait, les applications SIG dans les domaines de la santé se sont multipliées dans les années 90 et sont aujourd’hui en pleine expansion. L’analyse spatiale des données permet en effet aux géographes, comme aux professionnels de la santé, une approche nouvelle des phénomènes sanitaires qui sont traduits dans leur contexte géographique. L’utilisation récente des SIG en santé apporte des intérêts majeurs en épidémiologie et pour l’étude du système de soins, mais n’est pas sans limites ni contraintes, les données sanitaires n’étant quasiment jamais collectées au départ pour être intégrées dans un SIG.L’exemple de la conception d’un SIG pour étudier les maladies parasitaires dans la ville de Mbandjock au Cameroun permet d’illustrer l’intérêt et les limites des SIG pour analyser des données complexes et issues de sources très différentes. Les quartiers de cette ville, qui doit sa croissance à l’implantation d’un complexe agro-industriel sucrier dans les années 60, connaissent des disparités de situations parasitaires importantes, que l’utilisation des SIG aide à préciser ou à expliquer. Health data may be located and their spatial organization detected thanks to the Geographic Information System technologies. In fact, the GIS applications in the health sector multiplied in the nineties and are booming today. Data spatial analysis indeed enables geographers and health professionals to have a new approach towards medical phenomena in their geographical context. The health GIS recent use brings major interests in epidemiology and the care system study, but it has limitations and constraints, the medical data hardly ever being collected at the beginning to be integrated in a GIS.The example of a GIS creation to study parasitic diseases in Mbandjock in Cameroon makes it possible to illustrate the interest and the limitations of GIS to analyse complex data resulting from very different sources.Districts of this city which owes its growth to the establishment of a sugar industry in the sixties show important disparities of parasitic situations, that the use of GIS may help to specify or explain.

Background Tunisia is a hyper endemic country for human echinococcosis. The infection is transmitted via the eggs of Echinococcus granulosus which are passed in the faeces of the definitive canid host. Methods This study evaluated the contamination rate of the dog faeces in different climatic conditions at eight different geographic regions throughout Tunisia. Dog faecal samples were collected from the soil and the Echinococcus eggs were identified using microscopic and molecular (Eg1121/1122 PCR, Egss1 PCR and Nad1 PCR-RFLP) tools. Results The contamination index of dog faeces by E. granulosus eggs ranged from 8.3% to 41.3% depending on the region. Comparisons of the dog faecal contamination rate against human incidence found them to be independent. Neither human prevalence nor dog contamination index appeared to be related to climatic conditions or geographic characteristics. The genetic variability of E. granulosus samples was different within each region but was not related to geographic distance which is indicative of local divergent evolutions rather than isolation by distance. Conclusions A high environmental dog contamination index does not necessarily correspond to high prevalence in humans as transmission is strongly linked to human behavior and hygiene.

Background Risk assessment of tick-borne and zoonotic disease emergence necessitates sound knowledge of the particular microorganisms circulating within the communities of these major vectors. Assessment of pathogens carried by wild ticks must be performed without a priori, to allow for the detection of new or unexpected agents. Methodology/Principal Findings We evaluated the potential of Next-Generation Sequencing techniques (NGS) to produce an inventory of parasites carried by questing ticks. Sequences corresponding to parasites from two distinct genera were recovered in Ixodes ricinus ticks collected in Eastern France: Babesia spp. and Theileria spp. Four Babesia species were identified, three of which were zoonotic: B. divergens, Babesia sp. EU1 and B. microti; and one which infects cattle, B. major. This is the first time that these last two species have been identified in France. This approach also identified new sequences corresponding to as-yet unknown organisms similar to tropical Theileria species. Conclusions/Significance Our findings demonstrate the capability of NGS to produce an inventory of live tick-borne parasites, which could potentially be transmitted by the ticks, and uncovers unexpected parasites in Western Europe., Author Summary Diseases transmitted by ticks have diverse etiology (viral, bacterial, parasitic) and are responsible for high morbidity and mortality rates around the world, both in humans and animals. The emergence or re-emergence of tick-borne diseases is increasingly becoming a problem as the geographical distribution of several tick species is expanding, as well as the numbers of potential or known tick-borne pathogens are constantly evolving. It is thus necessary to know which microorganisms circulate within communities of this major vector to ensure adequate epidemiological surveillance. In this study, we evaluated the potential of Next-Generation Sequencing techniques (NGS) to produce, without a priori, an inventory of both predicted and non-expected parasites carried by Ixodes ricinus, the most prevalent human biting tick in France. Our findings suggest that NGS strategies could be used to produce an inventory of live parasites residing in ticks from a selected area, thereby expanding our knowledge base of tick-associated parasites.

International audience; Cryptosporidium parvum is a zoonotic protozoan parasite found worldwide, that develops only in the gastrointestinal epithelium and causes profuse diarrhea. Using a mouse model of C. parvum infection, we demonstrated by conditional depletion of CD11c+ cells that these cells are essential for the control of the infection both in neonates and adults. Neonates are highly susceptible to C. parvum but the infection is self-limited, whereas adults are resistant unless immunocompromised. We investigated the contribution of DC to the age-dependent susceptibility to infection. We found that neonates presented a marked deficit in intestinal CD103+ DC during the first weeks of life, before weaning, due to weak production of chemokines by neonatal intestinal epithelial cells (IEC). Increasing the number of intestinal CD103+ DC in neonates by administering FLT3-L significantly reduced susceptibility to the infection. During infections in neonates, the clearance of the parasite was preceded by a rapid recruitment of CD103+ DC mediated by CXCR3-binding chemokines produced by IEC in response to IFN gamma. In addition to this key role in CD103+ DC recruitment, IFN gamma is known to inhibit intracellular parasite development. We demonstrated that during neonatal infection CD103+ DC produce IL-12 and IFN gamma in the lamina propria and the draining lymph nodes. Thus, CD103+ DC are key players in the innate immune control of C. parvum infection in the intestinal epithelium. The relative paucity of CD103+ DC in the neonatal intestine contributes to the high susceptibility to intestinal infection.

Contains fulltext : 108727.pdf (Publisher’s version ) (Open Access) INTRODUCTION: In the era of malaria elimination and eradication, drug-based and vaccine-based approaches to reduce malaria transmission are receiving greater attention. Such interventions require assays that reliably measure the transmission of Plasmodium from humans to Anopheles mosquitoes. METHODS: WE COMPARED TWO COMMONLY USED MOSQUITO FEEDING ASSAY PROCEDURES: direct skin feeding assays and membrane feeding assays. Three conditions under which membrane feeding assays are performed were examined: assays with i) whole blood, ii) blood pellets resuspended with autologous plasma of the gametocyte carrier, and iii) blood pellets resuspended with heterologous control serum. RESULTS: 930 transmission experiments from Cameroon, The Gambia, Mali and Senegal were included in the analyses. Direct skin feeding assays resulted in higher mosquito infection rates compared to membrane feeding assays (odds ratio 2.39, 95% confidence interval 1.94-2.95) with evident heterogeneity between studies. Mosquito infection rates in membrane feeding assays and direct skin feeding assays were strongly correlated (p

National audience

Cryptosporidium, protozoaire parasite décrit en 1907 par Tyzzer, fut longtemps considéré comme un organisme commensal, rare et spécifique d’hôte. Après 1981, tous les auteurs s’accordèrent à penser que l’espèce C.parvum était commune à tous les mammifères, y compris l’homme, causant des diarrhées néonatales chez les ruminants, des diarrhées à guérison spontanée chez l’homme immunocompétent et des diarrhées cholériformes incurables chez l’homme immunodéficient. La cryptosporidiose était alors considérée comme une zoonose, l’homme s’infectant au contact des animaux malades ou au contact d’animaux de compagnie porteurs sains. Cependant, la cryptosporidiose peut se transmettre directement d’homme à homme comme le démontrent certaines épidémies dans des hôpitaux ou dans des centres aérés, ou indirectement par l’eau de boisson et les aliments souillés. Des recherches effectuées après plusieurs épidémies en Amérique du Nord et au Royaume Uni ont montré que toutes les eaux de surface (lacs, rivières...) sont contaminées par des cryptosporidies. Cette pollution serait principalement due à l’agriculture et à la faune sauvage. Les eaux d’égouts de populations infectées sont aussi source de contamination. Les procédés de traitement des eaux usées, filtration et désinfection, ne sont pas totalement efficaces pour éliminer complètement Cryptosporidium et des oocystes sont retrouvés dans l’eau de boisson. Depuis 1985, les recherches s’intensifient pour mettre au point des techniques fiables afin de déceler la présence des oocystes dans l’eau de boisson, de les identifier et de les inactiver., Described in 1907, Cryptosporidium, a protozoan parasite, was considered as a rare, commensal and specific organism. After 1981, C.paruum was recognized as a common source of contamination in all mammals including humans. Symptoms are neonatal diarrhea in ruminants and self limiting or life threatening diarrhea in immunocompetent or immunodeficient hosts, respectively. The first reports indicated that infected animals were the source of human infections and that cryptosporidiosis was a zoonotic disease. Nevertheless, cryptosporidiosis may be transmitted directly from person to person and indirectly by water. Pollution of all types of surface water, lakes, reservoirs, rivers etc can result from agriculture but sewage from infected populations are also a source of contamination. The sewage treatment processes, filtration and desinfection, are not fully effective and oocysts have been found in drinking water in North America and the United Kingdom. From 1985, studies have been carried out to enumerate, identify and inactivate Cryptosporidium oocysts in water.