Prevalence of Spotted Fever Group Rickettsia in North-Eastern Poland

Purpose: The north-eastern Poland is an endemic region of tick-borne diseases. The aim of the study is to assess the prevalence of anti-Rickettsia antibodies in the inhabitants of the north-eastern Poland and to assess the risk of acute infection (rickettsiosis) after a tick bite. Other aim was to assess the risk of co-infection with other pathogens after a tick bite. Methods: Two types of examinations were performed: serological and molecular. Serological analysis was performed in 82 foresters and 82 farmers with a history of tick bite. The molecular study was performed in 540 patients with various symptoms after a tick bite. The control group consisted of 20 honorary blood donors with no tick bites in anamnesis. Anti-Rickettsia spp. antibodies titres were determined by ELISA: Rickettsia SFG IgG ELISA (DRG International Inc. USA). PCR tests were performed towards Rickettsia spp. Borrelia burgdorferi, Anaplasma phagocytophilum. Results: In 64 (39.02%) farmers and foresters, anti-Rickettsia IgG antibodies were detected. The presence of anti-Rickettsia IgG antibodies was confirmed in 42 foresters (51.22%) and in 22 farmers (26.83%). In control group, results of all tests were negative. Rickettsia spp. DNA has not been confirmed in any out of 540 (0%) symptomatic patients. Conclusions: Seroprevalence of Rickettsia spp. infection in north-eastern Poland is high, especially in people often bitten by ticks, which makes this pathogen potentially dangerous for humans. Prevalence of anti-Rickettsia IgG antibodies in foresters is higher than in farmers. Symptomatic infection with Rickettsia spp. in humans in north-eastern Poland is uncommon.