Amplifying role of edible dormice in Lyme disease transmission in central Europe.

To determine whether the presence of edible dormice (Glis glis) amplifies the risk of human infection by the Lyme disease spirochete (Borrelia burgdorferi), the capacity of dormice as reservoir hosts was compared with that of other potential reservoirs in a central European site where risk of human infection is intense. Dormice appeared to be more heavily infested by subadult vector wood ticks (Ixodes ricinus) than were other reservoir hosts. Although their spirochete competence was similar to other reservoir hosts, field-derived dormice infected more ticks than did other rodents in the site, because nymphal ticks most readily feed on them. Spirochetes isolated from dormice appeared identical to those implicated as agents of Lyme disease. Subadult wood ticks become replete and detach from dormice during late afternoon when dormice are at rest in their nests. Thus, the presence of edible dormice in Central Europe amplifies transmission of the agent of Lyme disease and intensifies the risk of human infection.