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Kyasanur forest disease

Kyasanur forest disease
Classification and external resources

Kyasanur forest disease (KFD) is a tick-borne viral hemorrhagic fever endemic to South Asia.[1] The disease is caused by a virus belonging to the family Flaviviridae, which also includes yellow fever and dengue fever.


The disease was first reported from Kyasanur Forest of Karnataka in India in March 1957. The disease first manifested as an epizootic outbreak among monkeys killing several of them in the year 1957. Hence the disease is also locally known as Monkey Disease or Monkey Fever.[2] The similarity with Russian Spring-summer encephalitis was noted and the possibility of migratory birds carrying the disease was raised.[3] Studies began to look for the possible species that acted as reservoirs for the virus and the agents responsible for transmission. Subsequent studies failed to find any involvement of migratory birds although the possibility of their role in initial establishment was not ruled out. The virus was found to be quite distinctive and not closely related to the Russian virus strains. Antigenic relatedness is however close to many other strains including the Omsk hemorrhagic fever (OHF) and birds from Siberia have been found to show an antigenic response to KFD virus. Sequence based studies however note the distinctivenss of OHF.[4] Early studies in India were conducted in collaboration with the US Army Medical Research Unit and this led to controversy and conspiracy theories.[5][6]

Subsequent studies based on sequencing found that the Alkhurma virus, found in Saudi Arabia is closely related.[7] In 1989 a patient in Nanjianin, China was found with fever symptoms and in 2009 its viral gene sequence was found to exactly match with that of the KFD reference virus of 1957. This has however been questioned since the Indian virus shows variations in sequence over time and the exact match with the virus sequence of 1957 and the Chinese virus of 1989 is not expected. This study also found using immune response tests that birds and humans in the region appeared to have been exposed to the virus.[8] Another study has suggested that the virus is recent in origin dating the nearest common ancestor of it and related viruses to around 1942, based on the estimated rate of sequence substitutions. The study also raises the possibility of bird involvement in long-distance transfer.[9] It appears that these viruses diverged 700 years ago.[10]


There are a variety of animals thought to be reservoir hosts for the disease, including porcupines, rats, squirrels, mice and shrews.[11] The vector for disease transmission is Haemaphysalis spinigera, a forest tick. Humans contract infection from the bite of nymphs of the tick.


The disease has a morbidity rate of 2-10%, and affects 100-500 people annually.[1]

The symptoms of the disease include a high fever with frontal headaches, followed by haemorrhagic symptoms, such as bleeding from the nasal cavity, throat, and gums, as well as gastrointestinal bleeding.[11]

An affected person may recover in two weeks time, but the convalescent period is typically very long, lasting for several months. There will be muscle aches and weakness during this period and the affected person is unable to engage in physical activities.

Prevention and treatment[edit]

Prophylaxis by vaccination, as well as preventive measures like protective clothing, tick control, and mosquito control are advised. An attenuated live vaccine is now available. Specific treatments are not available.


  1. ^ a b EA Gould; T Solomon (February 9, 2008). "Pathogenic flaviviruses". The Lancet 371 (961): 500–509. doi:10.1016/S0140-6736(08)60238-X. ISSN 0140-6736. PMID 18262042. 
  2. ^ Nichter, Mark (1987). "Kyasanur Forest Disease: An Ethnography of a Disease of Development". Medical Anthropology Quarterly, New Series 1 (4): 406–423. doi:10.1525/maq.1987.1.4.02a00040. 
  3. ^ Work, Telford H.; Roderiguez, FR; Bhatt, PN (1959). "Virological Epidemiology of the 1958 Epidemic of Kyasanur Forest Disease". American Journal of Public Health 49 (7): 869–874. doi:10.2105/AJPH.49.7.869. PMC 1372906. PMID 13661478. 
  4. ^ Lin D, Li L, Dick D, Shope RE, Feldmann H, Barrett AD, Holbrook MR (2003). "Analysis of the complete genome of the tick-borne flavivirus Omsk hemorrhagic fever virus". Virology 313 (1): 81–90. doi:10.1016/S0042-6822(03)00246-0. PMID 12951023. 
  5. ^ Harry Hoogstraal, Makram N. Kaiser, Melvin A. Traylor, Ezzat Guindy, and Sobhy Gaber (1963). "Ticks (Ixodidae) on birds migrating from Europe and Asia to Africa, 1959-61". Bulletin World Health Organ. 28 (2): 235–262. PMC 2554471. PMID 13961632. 
  6. ^ Lewis, Michael (2002). "Scientists or Spies? Ecology in a Climate of Cold War Suspicion". Economic and Political Weekly 37 (24): 2324–2332. 
  7. ^ Charrel RN, Zaki AM, Attoui H, Fakeeh M, Billoir F, Yousef AI, de Chesse R, De Micco P, Gould EA, de Lamballerie X. (2001). "Complete coding sequence of the Alkhurma virus, a tick-borne flavivirus causing severe hemorrhagic fever in humans in Saudi Arabia". Biochem. Biophys Res. Commun. 287 (2): 455–61. doi:10.1006/bbrc.2001.5610. PMID 11554750. 
  8. ^ Jinglin Wang, Hailin Zhang, Shihong Fu, Huanyu Wang, Daxin Ni, Roger Nasci, Qing Tang, and Guodong Liang (2009). "Isolation of Kyasanur Forest Disease Virus from Febrile Patient, Yunnan, China". Emerg. Infect. Dis. 15 (2): 326–328. doi:10.3201/eid1502.080979. PMC 2657630. PMID 19193286. 
  9. ^ Rajeev Mehla, Sandeep R.P. Kumar, Pragya Yadav, Pradip V. Barde, Prasanna N. Yergolkar, Bobbie R. Erickson, Serena A. Carroll, Akhilesh C. Mishra, Stuart T. Nichol, and Devendra T. Mourya (2009). "Recent Ancestry of Kyasanur Forest Disease Virus". Emerging Infectious Diseases 15 (9): 1431–1437. doi:10.3201/eid1509.080759. PMC 2819879. PMID 19788811. 
  10. ^ Dodd KA, Bird BH, Khristova ML, Albariño CG, Carroll SA, Comer JA, Erickson BR, Rollin PE, Nichol ST (2011) Ancient ancestry of KFDV and AHFV revealed by complete genome analyses of viruses isolated from ticks and mammalian hosts. PLoS Negl Trop Dis 5(10):e1352.
  11. ^ a b Gerhard Dobler (27 January 2010). "Zoonotic tick-borne flaviviruses". Veterinary Microbiology 140 (3–4, Zoonoses: Advances and Perspectives): 221–228. doi:10.1016/j.vetmic.2009.08.024. ISSN 0378-1135. PMID 19765917. 


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