Kyasanur forest disease has been first reported in Shimoga district of Westren Mysore in Southern India. It is caused by a flavivirus of group B arbovirus labeled as kyasanur forest disease virus.
The disease is seen in people who visit the forest where monkeys are dying and there monkeys harbour the virus. Man is infected by the bite of wood tick – H. spinigera. The incubation period is 4-6 days. Onset of the disease is abrupt characterized by fever, headache, myalgia, and chills.
There is cough, vomiting, diarrhea and pain in the back along with photo-phobia. Bleeding tendencies in the form of epistaxis and haematemesis are present in some. Fever usually lasts from 6 to 11 days. After an a-febrile phase in more than half of the patients, there is recurrence of fever, headache, neck rigidity, toxaemia, stupor and lymphadenopathy in neck and axilla.
Patient generally recovers without any sequelae. Convalescence is often prolonged. Laboratory investigations show leukopenia and thrombo cytopenia. CSF exam shows rise in pressure with rise in proteins and cell count.
Diagnosis of kyasanur forest disease is based upon isolation of virus from blood and four fold rise in antibody titres in paired specimens of blood taken at 3 weeks interval.
Treatment is symptomatic. Disease carries a mortality of 5-10 per cent. No vaccine is available for prevention of the disease.