Borrelia burgdorferi Infection in Bird-feeding and Questing Ticks in Bulgaria

The presence of Borrelia burgdorferi sensu lato (the agent of Lyme disease) in Ixodes ricinus ticks removed from wild birds and questing ticks was investigated. A total of 345 ticks from 75 infested birds belonging to 10 species and 274 questing ticks collected from the surrounding vegetation were examined by PCR for Borrelia burgdorferi s. l. Pathogen DNA was found in 8.1% (28/345) of the bird-feeding ticks – 10.9% (11/101) in larvae and 7.0% (17/244) in nymphs. Prevalence of infection was 9.4% in ticks from the Eurasian blackbird (Turdus merula), 4.0% in ticks from the song thrush (T. philomelos) and 16.6% from the European robin (Erithacus rubecula). Detection of infected larvae (13.3%) collected from the Eurasian blackbird suggests that this species might contribute to the transmission to the vector I. ricinus. The overall prevalence of B. burgdorferi in the questing nymphs was 10.6%. This is the first report of B. burgdorferi s. l. infection in I. ricinus from wild birds in Bulgaria.