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  • Publication
    Métadonnées seulement
    Identification of host bloodmeal source and Borrelia burgdorferi sensu lato in field-collected Ixodes ricinus ticks in Chaumont (Switzerland)
    (2007)
    Cadenas, Francisca Moran
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    Humair, Pierre-François
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    Moret, Jacqueline
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    To evaluate the importance of vertebrate species as tick hosts and as reservoir hosts in two endemic areas for Lyme borreliosis in Switzerland, we applied molecular methods for the analysis of bloodmeal source and Borrelia infection in questing Ixodes ricinus L. ticks. In total, 1,326 questing ticks were simultaneously analyzed for Borrelia and for blood meal remnants by using reverse line blot. An overall infection prevalence of 19.0% was recorded for Borrelia sp., with similar rates in both sites. Using a newly developed method for the analysis of bloodmeal targeting the 12S rDNA mitochondrial gene, identification of host DNA from field-collected ticks was possible in 43.6% of cases. Success of host identification at the genus and species level reached 72%. In one site, host identification success reached its maximum in spring (93% in May), decreasing in summer (20% in July) and rising in autumn (73% in October). In the other site, identification rate in ticks remained low from April to July and increased in autumn reaching 68% in October and November. The most prevalent identified host DNA was artiodactyls in both sites. Red squirrel DNA was significantly more frequently detected in ticks collected in one site, whereas insectivore DNA was more frequent in ticks in the other site. DNA from more than one vertebrate host was detected in 19.5% of nymphs and 18.9% of adults. Host DNA was identified in 48.4% of the Borrelia infected ticks. Although DNA from all Borrelia species was found in at least some ticks with DNA from mammals and some ticks with DNA from birds, our results confirm a general association of B. afzelii and B. burgdorferi sensu stricto with rodents, and B. valaisiana and B. garinii with birds.
  • Publication
    Métadonnées seulement
    Prevalence of Borrelia burgdorferi sensu lato in ticks collected from migratory birds in Switzerland
    (2006)
    Poupon, Marie-Angèle
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    Humair, Pierre-François
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    ; ;
    Schaad, Michael
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    Jenni, Lukas
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    The prevalence of ticks infected by Borrelia burgdorferi sensu lato on birds during their migrations was studied in Switzerland. A total of 1,270 birds captured at two sites were examined for tick infestation. Ixodes ricinus was the dominant tick species. Prevalences of tick infestation were 6% and 18.2% for birds migrating northward and southward, respectively. Borrelia valaisiana was the species detected most frequently in ticks, followed by Borrelia garinii and Borrelia lusitaniae. Among birds infested by infected ticks, 23% (6/26) were infested by B. lusitaniae-infected larvae. Migratory birds appear to be reservoir hosts for B. lusitaniae.
  • Publication
    Métadonnées seulement
    Transmission of Borrelia afzelii from Apodemus mice and Clethrionomys voles to Ixodes ricinus ticks: differential transmission pattern and overwintering maintenance
    (1999)
    Humair, Pierre-François
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    This study deals with the ecology of Lyme borreliosis in Europe. The relationships between Borrelia burgdorferi sensu lato spirochetes, Clethrionomys and Apodemus rodent reservoirs and the Ixodes ricinus tick vector were investigated during 16 consecutive months in an enzootic area in Switzerland. Cultivation of ear skin biopsies was used to isolate spirochetes from C. glareolus, A. sylvaticus, A. flavicollis and Glis glis. Borrelia infection was more frequently observed in Clethrionomys than in Apodemus. Tick xenodiagnosis was used to determine the infectivity of rodents. The infection rate in licks fed on Clethrionomys was higher than that in licks fed on Apodemus, but Apodemus yielded more infected ticks than Clethrionomys because of a better tick moulting success. Xenodiagnostic ticks were placed into BSK medium to obtain isolates. Isolates from rodents and rodent-feeding ticks were all identified as B. afzelii. The follow-up of the infectivity status of repeatedly recaptured rodents clearly demonstrated that these hosts remained infective for ticks during winter till the following spring. Comparing C. glareolus and A. sylvaticus, each rodent species showed different host infection, different host infectivity and contributed differently to the moulting success of feeding ticks. These factors influence differentially the pattern of transmission of B. afzelii from Clethrionomys voles and Apodemus mice to I. ricinus ticks.
  • Publication
    Métadonnées seulement
    Relationship between Borrelia burgdorferi sensu lato species, red squirrels (Sciurus vulgaris) and Ixodes ricinus in enzootic areas in Switzerland
    (1998)
    Humair, Pierre-François
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    The infection and reservoir status of red squirrels (Sciurus vulgaris) for Borrelia burgdorferi sensu late were studied in Switzerland. B. burgdorferi sensu late 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 late 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. (C) 1998 Elsevier Science B.V. All rights reserved.
  • Publication
    Métadonnées seulement
    Transmission cycles of Borrelia burgdorferi sensu lato involving Ixodes ricinus and/or I-hexagonus ticks and the European hedgehog, Erinaceus europaeus, in suburban and urban areas in Switzerland
    (1997) ;
    Rouvinez, Evelyne
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    Toutoungi, Lina Naime
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    Godfroid, Edmond
    European hedgehog, Erinaceus europaeus Linnaeus, 1758, is a common host of Ixodes ricinus L, and I. hexagonus Leach, vectors of the Lyme disease spirochaete, Borrelia burgdorferi sensu lato. TO investigate whether hedgehogs are reservoirs for B. burgdorferi, hedgehogs were captured in a suburban area suitable for both tick species and in an urban area where I, ricinus is absent. The infection status of the hedgehogs was determined by xenodiagnosis using I. ricinus and I. hexagonus larvae. I. hexagonus and/or I. ricinus were found on;ll hedgehogs (n = 8) from the suburban area. In contrast, only I. hexagonus was infesting animals (n = 5) from the urban area. A total of 12/13 hedgehogs harboured B. burgdorferi infected ticks. Xenodiagnostic I. ricinus and I. hexagonus larvae that fed on hedgehogs became infected. The results clearly show that European hedgehogs are reservoir hosts of the Lyme disease spirochetes. DNA of B. burgdorferi sensu stricto, B. garinii and B. afzelii was detected in culture from ear biopsy and needle aspiration material and characterized by using a genospecies-specific PCR assay. One hedgehog presented a mixed infection of the skin with B, burgdorferi sensu stricto and B. garinii. This study also identifies an enzootic transmission cycle in an urban area involving E. europaeus and I. hexagonus. The close association of I. hexagonus with the burrows of its hosts mean that the risks of contact between I. hexagonus and humans may be low.