Pathogens and host DNA in Ixodes ricinus nymphal ticks from a German forest.

Unfed nymphs of Ixodes ricinus were collected from vegetation in a forest on the outskirts of Berlin, Germany and were analyzed for host and pathogen DNA. Pathogens were detected in 47% of the ticks. Borrelia afzelii was the commonest pathogen detected, followed by Rickettsia helvetica. Other pathogens included B. valaisiana, B. garinii, B. burgdorferi sensu stricto, Anaplasma phagocytophilum, and a relapsing fever-like Borrelia. Most of the host DNA detected was of rodent origin and was associated with infection by B. afzelii, R. helvetica, and A. phagocytophilum. Bird DNA was associated with B. valaisiana and B. garinii, and ruminant DNA with A. phagocytophilum. B. afzelii was also found in two ticks that contained bird DNA.