A total of 963 subjects in four groups from western and central Bohemia were examined in 1998-2000 for the presence of antibodies against granulocytic ehrlichiae. In the indirect fluorescence assay, a speciflc antigen from ehrlichiae (HGE) cultivated in-vitro and commercial anti-IgG and anti-IgM secondary antibodies were used.An overall prevalence of HGE antibodies of the class IgG corresponding to titres <<-1/SO and<-1/160 was found to be 21.0 and 13.5 %,respectively,with a predominance during the warm season (May-October).The seasonal seroprevalence was discriminated best from an all-year background by titres 1/SO-1/160.Elevated antibodies were found more frequently in older subjects;no effect of gender was observed.Antibodies of the class IgM were detected only exceptionally and did not exceed the titre of 1/40.Only minor differences were observed in the prevalence of HGE antibodies between groups differing geographically or by the presence of Borrelia antibodies. The seasonal incidence of HGE antibodies did not differ significantly from that of Borrelia antibodies.

        Key words: Ehrlichia -human granulocytic ehrlichiosis (HGE) - seroprevalence of immunoglobulins - seasonal incidence - diagnostic titres