Coinfection of Ixodes ricinus (Acari: Ixodidae) in northern Poland with the agents of Lyme borreliosis (LB) and human granulocytic ehrlichiosis (HGE).

Adult Ixodes ricinus ticks were collected from Pomerania province, northern Poland, to determine the presence of infection with agents of human granulocytic ehrlichiosis (HGE) and Lyme borreliosis by using the polymerase chain reaction (PCR). Of the 424 ticks 19.2% and 11.6% contained ehrlichiae and spirochetes, respectively. Frequency of single infection with the HGE agent was 63/424 while frequency of single infection with Borrelia burgdorferi sensu lato was 28/424. As many as 21/424 ticks (5%) contained both pathogens. This finding supports suggestions that both HGE agent and B. burgdorferi s. l. perpetuate in the same foci and frequently co-infect the same tick vector thereby increasing the risk of humans acquiring mixed infection.