Borrelia burgdorferi sensu lato genospecies in Ixodes ricinus ticks feeding on passerine birds in southern Norway

Abstract

Birds are increasingly considered important in the  global dispersal of tick-borne pathogens. The purpose of this study was to investigate the prevalence of Borrelia burgdorferi sensu lato genospecies in Ixodes ricinus ticks collected on passerine birds from two ornithological stations (Jomfruland and Lista) in southern Norway. In both sampling sites a total of 608 (109 larvae and 499 nymphs) of immature ticks were collected from 157 infested birds representing 26 species. The presence of B. burgdorferi s.l. DNA in ticks was tested using direct PCR amplification of the ospA gene, localized on lp-54 plasmid in B. burgdorferi s.l. genome. Twenty one out of 157 infested (13%) birds carried B. burgdorferi s.l. infected Ixodes ricinus ticks. B. burgdorferi s.l. DNA was detected in 19.7% of the tick samples. In total, 6.4% of larvae (7/109) and 10% of nymphs (50/499) were positive. The vast majority of infected ticks were found on blackbird (Turdus merula). The most frequent genospecies was B. garinii (85.5%), followed by B. afzelii (9.0%) and B. valaisiana (5.5%). Five different B. garinii genotypes were identified. Our findings showed that the blackbirds may support the circulation and spread of B. garinii and B. valaisiana. B. garinii was not detected in questing ticks from investigated locations. B. afzelii genospecies, however, dominated in questing ticks, rodents and ticks from rodents.