Human exposure to Crimean-Congo hemorrhagic fever virus is associated with livestock management and handling practices in southcentral Tanzania, 2023–2024

Background Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne zoonotic pathogen widely distributed across Africa, Asia, and Europe. Human infection occurs through tick bites or contact with infected animal tissues. In Tanzania, evidence of human exposure exists, but data on population-level seroprevalence and associated behavioral risk factors remain limited. This study assessed human CCHFV seroprevalence and identified demographic, behavioral, and environmental factors associated with prior exposure in livestock-keeping communities in southcentral Tanzania. Methods A community-based cross-sectional study was conducted in four districts of southcentral Tanzania during 2023–2024. A total of 850 adults completed structured questionnaires on demographic and behavioral factors and provided blood samples. Serum samples were tested for CCHFV IgG antibodies using a commercial ELISA. Logistic regression models were used to identify factors associated with seropositivity. Results Overall CCHFV seroprevalence was 3.41% (29/850). Seroprevalence increased with age and was highest among participants aged ≥ 51 years (6.28%, p = 0.044). In multivariable analysis, three factors were significantly associated with seropositivity: households with three or more children under five years of age (adjusted OR = 3.45, 95% CI 1.13–10.53, p = 0.030); butchering and consuming animals that died of illness (adjusted OR = 5.48, 95% CI 1.96–15.36, p = 0.001); and grazing animals on private land without other livestock, which was protective (adjusted OR = 0.32, 95% CI 0.12–0.90, p = 0.030). Conclusions Human CCHFV exposure in southcentral Tanzania is associated with household composition, animal-handling practices, and grazing behaviors. These findings highlight modifiable behavioral risk factors that may inform targeted public health interventions. As this study focuses on human serologic evidence of prior exposure, further integrated human–animal investigations are needed to better understand transmission dynamics.