Seroprevalence of Babesia divergens infection among forestry workers in Slovenia

The aim of the present study was to determine the prevalence and incidence of infection with Babesia divergens during the period of tick activity in immunocompetent participants, and to compare the seroprevalence of infection in forestry workers and indoor workers in Slovenia. The prospective study included 215 immunocompetent participants, 122 randomly selected forestry workers and 93 indoor workers. All the study participants were examined twice in 2002: in early spring before the beginning of tick activity and in late autumn at the end of seasonal tick activity. Before the tick season, a reactive (⩾1:16) B. divergens IgG titer determined with an immunofluorescence assay was found in 17.7% of all the study participants. IgG titers ⩾1:64, ⩾1:128, and ⩾1:256 were found in 8.4%, 5.6%, and 2.8% of all the study participants, respectively. There was no statistically significant difference in the prevalence of the B. divergens IgG titer between the forestry workers and the indoor workers. During the period of seasonal tick activity, one asymptomatic participant experienced at least a fourfold increase in B. divergens IgG titer, while in 5.6% less than a fourfold increase in B. divergens IgG titer was noted. In conclusion, the B. divergens IgG prevalence among foresters and indoor workers in Slovenia proved to be higher than expected from the only sporadic case reports of human babesiosis in Europe, but was comparable to the results of the few other European seroepidemiologic studies. In order to establish the prevalence in connection with the medical relevance of babesia infection for humans in Slovenia, additional research is required.