Prevalence of antibodies to spotted fever group rickettsiae in the region of Split (southern Croatia).

The prevalence of IgG antibodies to spotted fever group rickettsiae (SFG) was investigated by the indirect immunofluorescence assay in a sample of 1207 healthy residents of the central part of southern Croatia (eastern coast of Adriatic Sea). Sera obtained from subjects living in three different places of residency (urban, suburban and rural environs of the region) were tested. Overall 528 (43.7%) persons had significant antibody titers (1:40 or higher), with a significantly higher prevalence in suburban and rural areas. The results show that inhabitants in the area are clearly being exposed to SFG rickettsiae. Risk factors significantly associated with seropositivity to SFG rickettsiae were: living in suburban and rural settlements (odds ratio [OR] = 1.81; 95% confidence interval [CI] = 1.35-2.4), contact with animals (OR: 1.52; 95% CI: 1.15-1.99), and increase of age (OR: 1.18; 95% CI: 1.09-1.26).