Low sero-prevalence of Lyme borreliosis in the forested mountainous area of Gorski Kotar, Croatia

Aim. Clinical forms of Lyme disease in Gorski Kotar have occurred only spor adically, in contrast to the northwestern Croatia and the neighboring areas of Slovenia, which are well-known Lyme borreliosis endemic regions. Our ai m was to assess the level of sere-prevalence of Borrelia burgdorferi sensu late in a high-risk population of forestry workers in the mountainous regio n of Gorski Kotar, Croatia, and compare it with the sere-prevalence in the residents of that area and the neighboring littoral region. Methods. A sero-epidemiological study was conducted on 520 healthy subjects , divided in 3 groups: the first group included 234 forestry workers, resid ents of Gorski Kotar, the second 100 residents of various professions in th e same region, and the third 186 subjects of various professions from the n eighboring littoral region. The sera were collected during the winters of t wo successive years, 1997 and 1998. Lyme borreliosis serology was performed by indirect immunofluorescence assay. Sera from 10 hunting dogs from Gorsk i Kotar were also analyzed. Results. The IgG antibodies to B. burgdorferi sensu late were found in 11 e xaminees (4.7%) from the group of forestry workers, in 3 (3%) from the seco nd group, and in 5 (2.7%) from the third group. Four out of 10 dogs (40%) h ad IgG antibodies against B. burgdorferi. Conclusion. Our results show that the forest and mountainous area of Gorski Kotar, Croatia, has the characteristics of a low sere-prevalence area, in contrast to the endemic neighboring areas.