title: Seasonality of Ixodes ricinus ticks on vegetation and on rodents and Borrelia burgdorferi sensu lato genospecies diversity in two Lyme borreliosis-endemic areas in Switzerland.
abstract: We compared Ixodes ricinus questing density, the infestation of rodents by immature stages, and the diversity of Borrelia burgdorferi sensu lato (sl) in questing ticks and ticks collected from rodents in two Lyme borreliosis (LB)-endemic areas in Switzerland (Portes-Rouges [PR] and Staatswald [SW]) from 2003 to 2005. There were variations in the seasonal pattern of questing tick densities among years. Questing nymphs were globally more abundant at PR than at SW, but the proportion of rodents infested by immature ticks was similar (59.4% and 61%, respectively). Questing tick activity lasted from February to November with a strong decline in June. The seasonal pattern of ticks infesting rodents was different. Ticks infested rodents without decline in summer, suggesting that the risk of being bitten by ticks remains high during the summer. Rodents from SW showed the highest infestation levels (10±21.6 for larvae and 0.54±1.65 for nymphs). The proportion of rodents infested simultaneously by larvae and nymphs (co-feeding ticks) was higher at SW (28%) than at PR (11%). Apodemus flavicollis was the species the most frequently infested by co-feeding ticks, and Myodes glareolus was the most infective rodent species as measured by xenodiagnosis. At PR, the prevalence of B. burgdorferi sl in questing ticks was higher (17.8% for nymphs and 32.4% for adults) than at SW (10.4% for nymphs and 24.8% for adults), with B. afzelii as the dominant species, but B. garinii, B. burgdorferi sensu stricto, and B. valaisiana were also detected. Rodents transmitted only B. afzelii (at PR and at SW) and B. bavariensis (at SW) to ticks, and no mixed infection by additional genospecies was observed in co-feeding ticks. This implies that co-feeding transmission does not contribute to genospecies diversity. However, persistent infections in rodents and co-feeding transmission contribute to the perpetuation of B. afzelii in nature.
authors.affiliation: Institute of Biology, Laboratory of Eco-Epidemiology of Parasites, Université de Neuchâtel, Neuchâtel, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Pérez
authors.forename: Yvan
authors.initials: Y
authors.lastname: Kneubühler
authors.forename: Olivier
authors.initials: O
authors.lastname: Rais
authors.forename: Lise
authors.initials: L
authors.lastname: Gern
mesh_terms: D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology / Q000502:physiology*; D003411:Arvicolinae; D015748:Borrelia burgdorferi Group / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics; D004197:Disease Reservoirs; D006801:Humans; D018884:Ixodes / Q000382:microbiology / Q000502:physiology*; D007814:Larva; D008193:Lyme Disease / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission; D051189:Murinae; D009758:Nymph; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012376:Rodent Diseases / Q000453:epidemiology* / Q000469:parasitology; D012621:Seasons; D012788:Shrews; D013557:Switzerland / Q000453:epidemiology; D013984:Tick Infestations / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D015047:Zoonoses
chemical_list: D004269:DNA, Bacterial