A POPULATION-BASED SEROEPIDEMIOLOGIC STUDY OF HUMAN GRANULOCYTIC EHRLICHIOSIS AND LYME BORRELIOSIS ON THE WEST-COAST OF SWEDEN

Ehrlichioses are emerging infections in the United States. Human granu locytic ehrlichiosis (HGE) and Lyme borreliosis (LB) are acquired afte r Ixodes ricinus-complex tick bites. An ongoing seroepidemiologic stud y of the 185 of the 356 permanent residents of the Koster Islands in S weden was expanded to include ehrlichioses. Ehrlichial antibodies were measured by IFA using Ehrlichia equi and Ehrlichia chaffeensis. Borre lia burgdorferi IgG ELISA-seropositive subjects were confirmed by West ern blot, E. equi and E. chaffeensis antibodies (titer greater than or equal to 80) were found in 21 (11.4%) and 2 (1.1%) of 185 samples, re spectively. Antibodies to B. burgdorferi were found in 25 (13.5%) of 1 85. Six persons were seropositive for both HGE and LB. Among data from questionnaires, clinical symptoms, antibiotic treatments, or tick bit es were not more frequent in E. equi- or B. burgdorferi-seropositive t han -seronegative persons. The seroprevalence of HGE was similar to th at of Lyme borreliosis. Prospective studies of European HGE are needed .