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 and the incidence of vector-borne diseases. Objective: We aimed to identify the relationships between the prevalence of two tick-borne infectious agents, Anaplasma phagocytophilumand Borrelia burgdorferis.l., in small mammal communities and the landscape structure. Methods: Small mammals were sampled in 24 sites along a gradient of woodland fragmentation and hedgerow network density, and screened for infectious agents with rt-PCR techniques. Functional 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 mouse( Apodemussylvaticus), as well as structural variables (composition and configuration) of the surrounding landscape at various scales (50-500 m) were computed for each site. Results: The A. phagocytophilum prevalence increased with wooded habitats cover (50-500 m), which is explained by host population size, and increased also slightly with Bank voleabundance, which has a higher reservoir competence than Wood mouse. The B. burgdorferi s.l. prevalence only locally increased with wooded ecotones(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 life traits of infectious agents (e.g. host specificity) and the host species community ecologyto better understand the influence of the landscape structure on the spatial distribution of vector-borne infectious agents.