Kyasanur Forest disease is caused by Kyasanur forest disease virus, a tick-borne flavivirus genetically close to the Russian spring-summer encephalitis group that produces hemorrhagic fever rather than encephalitis [2][1]. It was isolated in 1957 from samples of dead wild primates and humans during an outbreak in Karnataka, India [1].
Disease overview
Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026
Kyasanur Forest disease is a tick-borne viral illness first recognized in 1957 near the Kyasanur forest of Karnataka, India, where it affected local residents and wild nonhuman primates [1]. The causative virus is related to the Russian spring-summer encephalitis complex but produces a hemorrhagic syndrome rather than neurologic disease [1]. Annual incidence in India is estimated at 400–500 cases, and the disease remains historically understudied [1].
Read the full clinical and epidemiological profile 6
The disease frequently presents as a hemorrhagic syndrome, distinguishing it from related tick-borne flavivirus infections that typically cause neurologic disease [1]. Its association with illness in wild primates is also a notable feature of the described outbreaks [1].
The disease was first documented as a severe outbreak in spring 1957 among people and wild nonhuman primates near the Kyasanur forest in Karnataka, India [1]. Estimated annual incidence in India is 400–500 cases, with most knowledge derived from studies in the late 1950s and early 1960s [1]. A 2012 report indicated possibly the largest number of cases since 2005, underscoring persistent knowledge gaps [1].
The probable tick vector of Kyasanur forest disease virus is Haemaphysalis spinigera [1]. The virus is maintained in a tick-borne transmission cycle and was associated with infection in wild nonhuman primates as well as humans [1].
A vaccine is currently in use in India for Kyasanur Forest disease, though its long-term efficacy may warrant further improvement [1]. Avoidance of tick exposure via the identified vector Haemaphysalis spinigera is implied by the tick-borne transmission route [1].
- 1 Holbrook MR et al. Kyasanur forest disease. Antiviral Res. 2012 Dec. PMID: 23110991. doi: 10.1016/j.antiviral.2012.10.005. PubMed: https://pubmed.ncbi.nlm.nih.gov/23110991/
- 2 Gritsun 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/
- A98.2
- 1D47.Y
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Recent related research
Kyasanur Forest Disease: feasible strategies for vaccine development and evaluation
The Lancet Regional Health - Southeast Asia
Comparative Sequence Analysis of the Envelope Gene of Kyasanur Forest Disease Virus Vaccine Strain With Currently Circulating Field Strains.
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Identification of bio-climatic determinants and potential risk areas for Kyasanur forest disease in Southern India using MaxEnt modelling approach
BMC Infectious Diseases
Development and evaluation of reverse transcription loop-mediated isothermal amplification for rapid and real-time detection of Kyasanur forest disease virus
International Journal of Infectious Diseases
On the transmission pattern of Kyasanur Forest disease (KFD) in India
Infectious Diseases of Poverty
Showing 5 of 8 related publications.
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