Relationships between landscape structure and the prevalence of two tick-borne infectious agents, Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato, in small mammal communities

Context - By modifying ecosystems, land cover changes influence the emergence, the spread and the incidence of vector-borne diseases. Objective - This study aimed at identifying associations between landscape structure and the prevalence of two tick-borne infectious agents, Anaplasma phagocytophilum and Borrelia burgdorferi s.l., in small mammal communities. Methods - Small mammals were sampled in 24 sites along a gradient of woodland fragmentation and hedgerow network density, and screened for infectious agents with real-time PCR techniques. For each site, structural variables (composition and configuration) of the surrounding landscape at various scales (0–500 m) and variables of wooded habitats connectivity based on graph theory and least cost path distances for the two dominant species, bank voles (Myodes glareolus) and wood mice (Apodemus sylvaticus), were computed. Results - The A. phagocytophilum prevalence increased with wooded habitats cover (0–500 m), likely through host population size, and increased slightly with bank vole abundance, which has a higher reservoir competence than wood mouse. The B. burgdorferi s.l. prevalence increased with wooded ecotones only at local scales (50–100 m). Wooded habitats connectivity measures did not improve models built with simple land cover variables. A more marked spatial pattern was observed for the prevalence of A. phagocytophilum than B.burgdorferi s.l. Conclusions - This study highlights the interest of considering together the ecology of infectious agents (e.g. host specificity) and the host species community ecology to better understand the influence of the landscape structure on the spatial distribution of vector-borne infectious agents.