BORRELIA-BURGDORFERI IN A FOCUS OF LYME BORRELIOSIS - EPIZOOTIOLOGIC CONTRIBUTION OF SMALL MAMMALS

The contribution of woodmice (Apodemus sylvaticus), yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) was c ompared in a focus of Lyme borreliosis in Switzerland during a 7 month s' study. All three species of mice and one species of shrews (Sorex a raneus) were shown parasitized by infected Ixodes ricinus immatures. A bout 14% of larvae and 50% of nymphs collected on small mammals were i nfected with B. burgdorferi. Spirochetes were isolated from blood of 3 woodmice and one yellow-necked mouse. The infectious status of rodent s was estimated by tick xenodiagnosis. Prevalence of infected rodents ranged from 20% to 44%. Mice presented a higher potential infectivity than voles. The prevalence of infected rodents showed a seasonal varia tion.