Omsk hemorrhagic fever (OHF) was first identified in the Omsk region of Russia in the 1940s. The virus responsible for OHF, known as Omsk hemorrhagic fever virus (OHFV), belongs to the Flavivirus genus, which also includes other viruses such as dengue, yellow fever, and West Nile virus. Sporadic outbreaks have occurred primarily in Siberia and Kazakhstan.
Gagarina et al. (1959) first noted that a disease found in muskrats was caused by a virus. This was later confirmed by Melentyeva and Fedorova. Konstantinov and Chudinov (1963) reported on Omsk outbreaks among hunters who came in touch with muskrats.
The transmission cycle involves two main hosts: ticks (Dermacentor reticulatus and Ixodes persulcatus) and muskrats (Ondatra zibethicus). Humans can contract OHF through tick bites or contact with infected animals’ blood or tissues.