Abstract
The circulation of an agent can be assessed by detecting it in vectors, hosts, or by indirect approaches using antibody detection in sampled hosts. When several host species are involved, a widely distributed host commonly exposed to the vector could be a useful sentinel for exposure risk. The roe deer (Capreolus capreolus) is a widely distributed mammal in Europe that has several interesting characteristics for consideration as a sentinel animal to infected ticks. The objective of the thesis was to evaluate the relevance of using serological data in deer to map the risk of exposure to the bacteria of the Borrelia burgdorferi sensu lato (Bbsl) complex responsible for Lyme disease in humans. To understand how to interpret serology maps, the temporal dynamics of anti-Bbsl antibody levels were determined. This was based on the analysis of samples collected over a period of 10 years in two wild deer populations where the same individuals are recaptured from one year to the next by Capture Marking Recapture (CMR). A relatively short persistence of antibody levels could be detected. This result was confirmed by monthly sampling of captive deer in pens at a third capture site. The results suggest that the serology is informing over a period close to the sampling. Following these results, hunting samples from several French departmental hunting federations were analyzed to determine the spatial aggregation of seropositive individuals at different time scales. The proportion of seropositive individuals and mean number of ticks weres also modelled according to other factors (environmental, meteorological, presence/absence of certain hosts and factors related to the individual). The results allowed the production of a predictive map of France where deer would be most exposed to Bbsl and where humans would also be most likely to be exposed. The works show that roe deer serology provides interesting initial elements for its use in the Bbsl surveillance. Finally, this type of approach could be interesting to extend to other tick-borne diseases in the context of epidemiological surveillance.