Evidence of ehrlichiosis agents found in ticks (Acari : Ixodidae) collected from migratory birds

Two Ehrlichia pathogens were found in immature Ixodes ricinus (L.) ticks co llected from migratory passerine birds in the Curonian Spit area of the Bal tic Region of Russia (Kaliningrad enclave). During the spring and fall of 2 000, 1,606 passerine birds (eight species) were collected; 6.8% of them (11 0/1,606) were infested by ticks, and 51.8% (57/110) of tick clusters contai ned various human pathogenic microorganisms. Human monocytic ehrlichiosis ( HME) and human granulocytic ehrlichiosis (HGE) agents were found in 14% (8/ 57) of cases. Borrelia afzelii, Borrelia garinii, and Borrelia burgdorferi sensu stricto were found in 92.9% (53/57) of the ticks. In five out of eigh t cases, infection of both Ehrlichia and Borrelia were obtained. In one cas e, a single nymph contained HME, B. afzelii, and B. garinii. Borrelina burg dorferi s.s. and B. afzelii were found together in one pool of four nymphs and one larva. All agents were identified, using polymerase chain reaction and species-specific primers, In 8.8% of the ticks collected from birds in the fall and 22% in the spring, pathogens were isolated from attached co-fe eding nymphs and larvae. These data demonstrate that Ehrlichia exchange cou ld occur between co-feeding ticks on animals without systemic infection.