Amélie Vaniscotte

Role of dog behaviour and environmental fecal contamination in transmission of Echinococcus multilocularis in Tibetan communities

On the Eastern Tibetan Plateau region (Sichuan province, China) dogs are regarded as important definitive hosts of Echinococcus multilocularis. We studied dog spatial behaviour in 4 Tibetan villages in order to determine the role of dogs in environmental contamination and their potential interactions with small mammal intermediate hosts. We identified definitive host species and Echinococcus spp. infection status of feces collected in the field by PCR methods and analysed the spatial distribution of canid feces. Nocturnal space utilization of GPS collared dogs in and around villages was also undertaken. E. multilocularis DNA was amplified in 23% of dog feces (n=142) and in 15% of fox feces (n=13) but this difference was not significant. However, dog feces were more frequently observed (78% of collected feces) than fox feces and are therefore assumed to largely contribute to human environment contamination. Feces were mainly distributed around houses of dog owners (0-200 m) where collared dogs spent the majority of their time. Inside villages, the contamination was aggregated in some micro-foci where groups of dogs defecated preferentially. Finally, small mammal densities increased from the dog core areas to grasslands at the periphery of villages occasionally used by dogs; male dogs moving significantly farther than females. This study constitutes a first attempt to quantify in a spatially explicit way the role of dogs in E. multilocularis peri-domestic cycles and to identify behavioural parameters required to model E. multilocularis transmission in this region.

Small-mammal assemblage response to deforestation and afforestation in central China

Abstract Deforestation is a major environmental issue driving the loss of animal and plant species. Afforestation has recently been promoted to conserve and restore Chinese forest ecosystems. We investigated the distribution of small-mammal assemblages in an area where forest and associated deforestation habitats dominate, and in an agricultural area where afforestation is ongoing in the Loess Plateau of southern Ningxia Autonomous Region, P.R. China. Multiple trapping was used. Assemblages were defined based on the multinomial probability distribution and information theory. Species turnover between assemblages of deforested and afforested habitats was high, although no clear effect on species richness was observed. The two assemblages described along the deforestation gradient displayed higher diversity, whereas diversity was lower in assemblages identified in afforested habitats where Cricetulus longicaudatus, a known agricultural pest in various areas of China, clearly dominated. The threatened Sorex cylindricauda and Eozapus setchuanus were recorded along the deforestation gradient but not in plantations. Therefore, habitats present along a deforestation succession in this part of Ningxia sustain a high diversity of small mammals and include species of conservation concern. At the present stage of its process (maximum 15 years), afforestation in southern Ningxia favours the dominance of an agricultural pest.

Towards understanding the impacts of environmental variation on Echinococcus multilocularis transmission

A key element in disease emergence/re-emergence is ecosystem disruption as a result of anthropogenic effects which may be as rapid as in forestry and agricultural changes. There is however difficulty in developing suitable models to study ecology of infectious diseases, wherein spatial determinants that meaningfully characterize wildlife reservoir habitat, can be linked in turn to host ecology and to dynamics of pathogen/parasite transmission. Spatial variables in the form of landscape and socio-economic characteristics should be linked to parasite transmission dynamics using an integrated modeling approach that takes into account multi-level heterogeneity at habitat, host and parasite domains and deterministic transmission parameters. The diversity of small mammals host communities and landscape worldwide offer a number of systems that sustain transmission of E. multilocularis at various time-space scales. It is expected that further advances will come from methods combining quantification of host communities from field surveys, landscape via remote sensing and parasite transmission via population screenings conducted on definitive hosts (e.g. dogs in villages in China or foxes in Europe) and humans, in a spatially explicit context. The combination of multi-level field approaches with modern regression techniques coupled with traditional transmission models provide a unique opportunity of investigating how a diversity of small mammal communities and anthropogenic landscapes can regulate parasite transmission.