Seroprevalence of Crimean-Congo hemorrhagic fever in southeastern Bulgaria.

Crimean-Congo hemorrhagic fever (CCHF), which is endemic in Bulgaria, is caused by the Crimean-Congo hemorrhagic fever virus (CCHFV). The seroprevalence of CCHFV in southeastern Bulgaria was examined in this study. For this purpose, a total of 751 human blood samples were collected and examined by indirect immunofluorescence assay. In addition, a questionnaire was completed for every participant. Anti-CCHFV antibodies were detected in 3.20% (24/751) of the tested sera. None of the seropositive individuals had a history of CCHF. The results indicate that the proportion of positive findings increase with age. The significant risk factors for CCHFV infection are tick bites (18.85%, 23/122), livestock breeding (6.15%, 16/260), and residing in rural areas (6.20%, 21/339).