Prevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in questing Ixodes ricinus ticks in relation to the density of wild cervids

Abstract

Background: Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum have been considered as pathogens in animals and humans. The role of wild cervids in the epidemiology is not clear. We analyzed questing Ixodes ricinus ticks collected in spring for these pathogens from sites with high (Fjell<o>yvar and Str<o>m) and low density (Tjore, Hinnebu and Jomfruland) of wild cervids to study the spread of the pathogens in questing ticks. Methods: For detection of Anaplasma phagocytophilum a 77-bp fragment in the msp2 gene was used. Detection of Borrelia burgdorferi sensu lato was performed using the FL6 and FL7 primers according to sequences of conserved regions of the fla gene. The OspA gene located on the linear 49-kb plasmid was used as target in multiplex PCR for genotyping. Genospecies-specific primers were used in the PCR for Borrelia burgdorferi sensu stricto, B. afzelii and B. garinii. Results: Infection rates with Borrelia spp. were significantly lower at Fjell<o>yvar and Str<o>m compared to Tjore and Hinnebu; Fjell<o>yvar vs. Tjore (chi2=20.27, p<0.0001); Fjell<o>yvar vs. Hinnebu (chi2=24.04, p<0.0001); Str<o>m vs. Tjore (chi2=11.47, p=0.0007) and Str<o>m vs. Hinnebu (chi2=16.63, p<0.0001). The Borrelia genospecies were dominated by. B. afzelii (82%) followed by B. garinii (9.7%) and B. burgdorferi sensu stricto (6.9%). B. burgdorferi s.s. was only found on the island of Jomfruland. The infection rate of Anaplasma phagocytophilum showed the following figures; Fjell<o>yvar vs Hinnebu (chi2=16.27, p=0.0001); Str<o>m vs. Tjore (chi2=13.16, p=0.0003); Str<o>m vs. Hinnebu (chi2=34.71, p<0.0001); Fjell<o>yvar vs. Tjore (chi2=3.19, p=0.0742) and Fjell<o>yvar vs. St<o>m (chi2=5.06, p=0.0245). Wild cervids may serve as a reservoir for A. phagocytophilum.[...]