Kyasanur Forest Disease (KFD) is a zoonotic disease associated with sudden onset of high grade fever, prostration, nausea, vomiting, diarrhea and occasionally neurological & haemorrhagic manifestations.
It derives its name from the forest range where the virus was first isolated. It is also known as “monkey disease/monkey fever” because of its association with monkey deaths.
The disease was first reported in 1957 from Shimoga district, Karnataka, which is a primitive sylvan territory in Western Ghats of India, subsequently spread centripetally to other districts of Karnataka viz., Chikkamagalore, Uttara Kannada, Dakshina Kannada and Udupi districts and to Chamarajanagar district in 2012 and Belagavi district in 2016.
2013, KFDV was detected in autopsy material of dead monkeys in Nilgiris district of Tamil Nadu state. Monkey deaths and human cases have now been reported from three neighbouring states bordering Karnataka viz., Wayanad (2013) and Malappuram districts of Kerala (2014), North Goa district of Goa state (2015) and Sindhudurg district of Maharashtra (2016). Recent incidence has been reported from Wayanad district, Kerala.
KFDV is transmitted by an infected tick, especially nymphal stage ticks. The wild monkeys Semnopithecus entellus and Macaca radiata, gets the disease through the bites of infected ticks. Infection causes severe febrile illness in most of the monkeys. When infected monkeys die, the ticks drop from their body, thereby generating “hot spots” of infectious ticks that further spread the disease. Humans can get the disease form an infected tick bite or by contact with an infected animal, such as sick or recently dead monkey. Available epidemiological data does not suggest any human-to-human transmission. However, human cases have been reported in the past while working on this virus in the laboratory.
The epidemic period usually begins in October or November and peaks from January to April, then declines by May and June. The epidemic/ outbreaks relates to the activity of nymphs, which is very high during November to May.
Incubation period : Estimated to be between 3 - 8 days after the bite of an infective tick.
(KFD) usually presents with sudden onset of high-grade fever with chills, intense frontal headache, severe myalgia and body aches. Muscle tenderness, photophobia, nausea, vomiting, and diarrhea are usually seen. Respiratory symptoms like persistent cough, may be present in some cases. Temperature may be as high as 104 0 F/40 0 C, and last for 5 - 12 days and there is intense prostration. In few cases hemorrhagic symptoms may occur in early stage in the form of bleeding from the nose, gums and intestines as evidenced by hematemesis or fresh blood in the stools. Some patients have persistent cough, with blood-tinged sputum and occasionally substantial hemoptysis but generally resolve soon.
In severe cases neurological symptoms like neck stiffness, mental disturbance, coarse tremors, giddiness, and abnormality of reflexes are noted.
he second phase of the illness occurs after the febrile phase, on an average, from day 8 onwards. This phase is initiated by headache, severe prostration progressing to signs and symptoms of central nervous system involvement in very few cases presenting as meningo-encephalitis.
Case fatality is 2 - 10%. Fatality is higher in the elderly and in patients with co-morbid conditions like - liver diseases (alcoholic) etc.
No specific treatment for KFD is available; however, prompt symptomatic and supportive therapy including maintenance of hydration, hemodynamic stability and management of neurological symptoms decreases morbidity and mortality.
KFD surveillance consists of three major components :
Application of repellants such as Dimethylphthalate (DMP), NN-Diethyl-m-Tolumaide (DEET) and certain other proprietary preparations having these or similar chemicals, e.g . Mylol on the exposed parts is effective from one to a few hours. If the duration of stay inside the forest is longer, more than one application may be necessary.
People living in the forest or visiting forest areas should strictly use tick repellents along with personal protection measures (long clothes by covering neck, chest, back, and legs) before going to the forest.
There is limited availability of information on KFD vaccine for human use in India. State Government of Karnataka is following KFD vaccination policy in the KFD endemic area.
Last Modified : 8/4/2022