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  • Publication
    Accès libre
    Relationship between Borrelia burgdorferi sensu lato species, red squirrels (Sciurus vulgaris) and Ixodes ricinus in enzootic areas in Switzerland
    (1998)
    Humair, Pierre-François
    ;
    The infection and reservoir status of red squirrels (Sciurus vulgaris) for Borrelia burgdorferi sensu lato were studied in Switzerland. B. burgdorferi sensu lato was isolated from 15 skin samples from 4/6 dead red squirrels, victims of road traffic. Isolates were identified using restriction fragment length polymorphism (RFLP): B. burgdorferi sensu stricto was present in 14 culture tubes containing skin samples and B. afzelii in two other tubes. A mixed infection was revealed in one case. A total of 227 ticks attached to squirrels were cultivated in BSKII medium and 90 isolates were obtained. Genotypic identification by RFLP showed that B. afzelii (59%) and B. burgdorferi sensu stricto (46%) dominated in ticks feeding on red squirrels. Data collected from one particular animal, highly infested with Ixodes ricinus and harbouring numerous Borrelia-infected Ixodes ricinus ticks, showed that transmission of B. burgdorferi sensu lato occurred from S. vulgaris to feeding ticks. More precisely, B. burgdorferi sensu stricto and B. afzelii were mainly transmitted from S. vulgaris to ticks. The present data emphasized the results obtained previously from small rodents and birds in Japan and in Switzerland, showing the occurrence of specific associations between host species and Borrelia genospecies.
  • Publication
    Accès libre
    Borrelia burgdorferi in a focus of Lyme borreliosis: epizootiologic contribution of small mammals
    Humair, Pierre-François
    ;
    Turrian, N
    ;
    ;
    The contribution of woodmice (Apodemus sylvaticus), yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) 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 (Sorex araneus) were shown parasitized by infected Ixodes ricinus immatures. About 14% of larvae and 50% of nymphs collected on small mammals were infected with B. burgdorferi. 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.