Crimean-Congo hemorrhagic fever (CCHF) is an emerging tickborne disease and a World Health Organization priority. Although humans are accidental hosts, infection can lead to hemorrhagic fever with a high fatality rate. Domestic animals play a critical role in disease transmission, but infected animals do not show clinical signs and viremia is short; thus, CCHF virus (CCHFV) infections can remain unobserved. During 2017-2019, we conducted 2 sequential observational studies followed by a multisite randomized controlled trial to determine spatial-temporal patterns and quantify drivers for CCHFV exposure in a natural host (sheep) in a CCHF-endemic area of Bulgaria. We found high-risk areas embedded in endemic regions. Animal characteristics were not correlated with seropositivity; however, a seasonality effect was observed, suggesting sampling time was a potential confounder. Force of infection varied across farms and over time. CCHFV transmission heterogeneity among farms is driven by preventive measures used to reduce exposure to ticks.
Journal article
2025-09-01T00:00:00+00:00
31
1738 - 1746
8
Bulgaria, CCHFV, Crimean-Congo hemorrhagic fever, Crimean-Congo hemorrhagic fever virus, control measures, exposure, force of infection, spatial-temporal, vaccine efficacy, vector-borne infections, viruses, zoonoses, Hemorrhagic Fever, Crimean, Bulgaria, Animals, Hemorrhagic Fever Virus, Crimean-Congo, Humans, Sheep, Ticks