Serological survey in persons occupationally exposed to tick-borne pathogens in cases of co-infections with Borrelia burgdorferi, Anaplasma phagocytophilum, Bartonella spp. and Babesia microti.

Sera of 39 farmers, 119 foresters and 32 blood donors were investigated for the presence of antibodies against B. burgdorferi, A. phagocytophilum, B. microti and Bartonella spp. Semi-quantitative indirect immunofluorescence test was used to measure titers of anti-A. phagocytophilum, B. microti and Bartonella spp. IgG. ELISA test was used to measure titers of anti-B. burgdorferi IgM and IgG. B. burgdorferi was the most frequently observed among all the examined pathogens. 27.7% of farmers, 23.1% of forestry workers and 37.5% of control group were infected with Bartonella spp. Anti-A. phagocytophilum and anti-B. microti reactions were observed rarely. Sera of persons with single infection dominated in farmers and forestry workers. Co-infection with 2 pathogens was observed more frequently in forestry workers and farmers than in the control group. Co-infections with 3-4 pathogens were observed only in forestry workers. Among the observed co-infections, the most frequent were: B. burgdorferi with Bartonella spp. and B. burgdorferi with A. phagocytophilum. Moreover, in forestry workers, triple coinfections with B. burgdorferi, Bartonella spp. and A. phagocytophilum and one quadruple coinfection were observed. Persons with occupational risk of tick bites, especially forestry workers, more often have anti-B. burgdorferi antibodies and are more often co-infected with various tick-borne pathogens than the persons from the control group. It seems that more often coinfections in persons with occupational risk of tick bites are a consequence of the higher incidence of infection with B. burgdorferi, as anti-B. microti, A. phagocytophilum and Bartonella spp. antibodies are not more commonly prevalent in persons with occupational risk of tick bites than in healthy volunteers.