<i>Borrelia burgdorferi</i> in a focus of Lyme borreliosis: epizootiologic contribution of small mammals

The contribution of woodmice (<i>Apodemus sylvaticus</i>), yellow-necked mice (<i>Apodemus flavicollis</i>) and bank voles (<i>Clethrionomys glareolus</i>) was compared in a focus of Lyme borreliosis in Switzerland during a 7 months' study. All three species of mice and one species of shrews (<i>Sorex araneus</i>) were shown parasitized by infected Ixodes ricinus immatures. About 14% of larvae and 50% of nymphs collected on small mammals were infected with <i>B. burgdorferi</i>. Spirochetes were isolated from blood of 3 woodmice and one yellow-necked mouse. The infectious status of rodents 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 variation.