Omsk hemorrhagic fever virus is a member of the genus Flavivirus, family Flaviviridae, and one of the tick-borne flaviviruses genetically closely related to TBEV [1][2]. Within this tick-borne flavivirus group it clusters with Kyasanur Forest disease virus and Alkhurma virus, which—like OHFV—produce hemorrhagic fever rather than encephalitis in humans, in contrast to TBEV, Louping ill virus, Langat virus, and Powassan virus, which primarily cause neuroinvasive disease [2].
Disease overview
Omsk hemorrhagic fever
鄂木斯克出血热
Evidence-backed informationEN 5/7 applicable sections · ZH 5/7 applicable sectionsUpdated Sep 3, 2026
Omsk hemorrhagic fever virus (OHFV) is a tick-borne flavivirus closely related to tick-borne encephalitis virus (TBEV), but distinguished by causing hemorrhagic disease rather than encephalitis in affected humans [1]. It belongs to the tick-borne flavivirus group together with Kyasanur Forest disease virus and Alkhurma virus, which similarly tend to produce fatal hemorrhagic fevers rather than neuroinvasive illness [2]. As a relative of TBEV, OHFV is embedded within the broader tick-borne flavivirus epidemiology of Eurasia, although its specific clinical and geographic patterns differ from those of the encephalitis-causing members of the complex [1].
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Within the tick-borne flavivirus group, OHFV is specifically associated with hemorrhagic fever rather than the encephalitic presentations produced by TBEV and its other close relatives [1][2]. The reviewed literature explicitly contrasts the hemorrhagic disease pattern of OHFV (along with Kyasanur Forest disease virus) with the predominantly encephalitic manifestations of the TBEV-complex viruses, including the biphasic milk fever and chronic encephalitis forms characteristic of TBEV infection [1][2].
Omsk hemorrhagic fever virus is discussed as a component of the tick-borne flavivirus group described in large reviews of the TBEV complex, rather than as an entity with its own published burden estimates in this evidence base [1][2]. It is presented alongside Kyasanur Forest disease virus and Alkhurma virus as viruses closely related to TBEV that "do not play an essential epidemiologic role in humans," in contrast to TBEV, which accounts for approximately 11,000 cases annually in Russia and about 3,000 cases in the rest of Europe [1][2].
Transmission patterns of OHFV are inferred from its placement within the tick-borne flavivirus group, for which ticks and their local hosts are highlighted as central to the maintenance and emergence of virus variants with differing pathogenic characteristics [2]. The reviews emphasize the role of ixodid tick vectors and their vertebrate hosts in shaping the ecology of these tick-borne flaviviruses, including OHFV [2].
Specific OHFV prevention measures are not detailed in the supplied evidence; however, given its identity as a tick-borne flavivirus, control strategies discussed for the broader group include addressing tick vectors, their local hosts, and the factors that drive emergence of new virus variants [2]. Modern vaccine development trends noted for the tick-borne flavivirus group involve attenuated and improved vaccine virus strains, though the specific applicability of these vaccines to OHFV is not specified in the evidence [1][2].
- 1Gritsun TS et al. Tick-borne flaviviruses. Adv Virus Res. 2003. PMID: 14714436. doi: 10.1016/s0065-3527(03)61008-0.PubMed: https://pubmed.ncbi.nlm.nih.gov/14714436/
- 2Gritsun TS et al. Tick-borne encephalitis. Antiviral Res. 2003 Jan. PMID: 12615309. doi: 10.1016/s0166-3542(02)00206-1.PubMed: https://pubmed.ncbi.nlm.nih.gov/12615309/
- A98.1
- 1D48
Coverage
Reporting countries and regions
Trends by reporting country
Monthly patterns over time
Data access
Page dataset index with source links and update metadata.
Official sourcesAuthority, cadence, notes1
JP NIID Weekly
Japan
Japan weekly infectious disease surveillance via NIID/JIHS.