Rate of infection ofIxodes ricinus ticks withBorrelia burgdorferi sensu stricto,Borrelia garinii,Borrelia afzelii and group VS116 in an endemic focus of Lyme disease in Italy

A study to evaluate the natural rate of infection ofIxodes ricinus withBorrelia burgdorferi sensu lato was carried out in an endemic focus of Lyme disease in the Trieste area in northern Italy. Two-hundred and twenty-seven ticks collected in ten different stations were tested individually for the presence of the spirochetes using polymerase chain reaction techniques able to identify bothBorrelia burgdorferi sensu lato and the four genospecies (Borrelia burgdorferi sensu stricto,Borrelia garinii, Borrelia afzelii and group VS116). Multiple infection of individual ticks was found. The infection rate ranged from 0–70%. Infection ofIxodes ricinus withBorrelia burgdorferi group VS116 was found for the first time in Italy in both a high and a low endemic focus of Lyme disease.