Determination of Seroprevalence and Risk Factors of Crimean-Congo Haemorrhagic Fever (CCHF) in the Endemic Region in Turkey: A Population-Based Cross-Sectional Study

Objectives. Turkey is one of the countries that has the most cases of CCHF in recent years among the endemic countries. The disease also poses an important health threat with high mortality rate. The aim of the study was to determine the seroprevalence and risk factors of CCHF in adults aged >= 20 years in Tokat in the endemic region, Turkey. Methods. In this population-based cross-sectional study, a total of 85 Family Medicine Units (FMUs), from over 170 in Tokat, were randomly selected using 50% sampling. The sample size was determined among the subjects aged >= 20 who registered with the FMUs, due to gender, age group, and the urban/rural population size of Tokat using the stratified cluster sampling method. Subjects were invited to the FMUs. A questionnaire was performed face to face. The blood samples were taken, and anti-CCHFV IgG antibodies were measured with ELISA method. Results. 1272 (54.9%) out of 2319 participants were female, and the mean age was 47.3 +/- 15.3. Anti-CCHFV IgG seropositivity was 5.6% (n = 130). Seropositivity rates in terms of adjusted odds ratios (AOR) were higher 2.53 times (95% CI: 1.57-4.08; p=0.001) in males; 4.05 (95% CI: 2.14-7.65; p<0.001) in age group >= 65; 0.33 (95% CI: 0.14-0.76; p<0.001) in graduates of high school and above; 0.71 (95%CI: 0.33-1.52; p<0.001) in ones with good income; 1.84 (95%CI: 1.18-2.86; p<0.001) in farmers; 1.64 (95% CI: 1.04-2.27; p<0.001) in people dealing with animal husbandry; and 1.02 (95% CI: 1.03-2.29; p<0.001) in those with history of tick contact. Conclusions. CCHF seroprevalence is still a common public health problem in Tokat, Turkey. Male gender, advanced age group, low-educated, low-income, farmers, animal husbandry, and history of tick contact were found to be risk factors for CCHF. The importance of this kind of community-based studies to identify the seroprevalence in regional and national level increases even more.