Seroepidemiology of Coxiella burnetii infection among blood donors in Albacete

The objectives of this study were to determine the prevalence of antibodies to Coxiella burnetii among blood donors and to examine the epidemiological characteristics of C. burnetii infection in Albacete, Spain. A total of 863 serum samples were collected from blood donors aged 18-65 years. Donor samples were stratified by age, sex, and residence (rural or urban). IgG and IgM titers to the C. burnetii phase II antigen were determined by an indirect immunofluorescence assay. The prevalence of anti-phase II IgG was 23.1%, and three (0.3%) donors had positive IgM titers. Men were more frequently seropositive than women (29% vs. 18%; OR: 1.85; 95% CI: 1.34-2.56), and this difference was not related to differential occupational exposure to animals. Pet ownership had no impact on seroprevalence. In contrast, occupations involving contact with domestic ungulates were associated with a higher seroprevalence (OR: 2.39; 95% CI: 1.04-5.48). Nevertheless, 90% of seropositive donors reported no contact with farm animals. Our results show that C. burnetii infection is highly endemic in Albacete and that most infections are not linked to specific occupational exposure in this area. The high prevalence of antibodies to C. burnetii among blood donors indicates the advisability of studies to determine the risk of transfusion-transmitted Q fever in endemic areas.