Kyasanur Forest Disease Monkey Disease or Monkey Fever

What is Kyasanur Forest Disease?

Kyasanur Forest disease is caused by a virus (Kyasanur Forest disease virus). The disease was first reported from Kyasanur Forest of Karnataka in India in March 1957 where monkeys were dying in the forest. The disease is also known locally as Monkey Disease or Monkey Fever. The virus seems to be primarily limited to Karnataka State of India with approximately 400-500 cases reported each year.

How do you get Kyasanur Forest Disease?

Hard ticks are the primary hosts of the virus. Rodents, bats and monkeys, bitten by the ticks, can also become hosts for the virus. Kyasanur Forest disease is transmitted to humans through the bite of a tick or through contact with an infected animal. No human-to-human transmission has been reported.

Although animals such as cows, goats and sheep may be bitten by the ticks and become hosts to the virus, transmission from these large animals to humans is rare. No transmission through the unpasteurized milk of these animals has been reported.

Susceptibility and Resistance

Kyasanur Forest disease is typically limited to the western and central parts of Karnataka State, India. However, monkeys and people have recently tested positive for the virus in other parts of India. All persons in these areas are susceptible, however those working and spending time in rural outdoor environments (farmers, herders, hunters, etc.) are more likely to encounter Hard ticks or other animal hosts of the virus.

The disease is most common during the dry season (November to June).

Incubation Period

The incubation period for Kyasanur Forest Disease is 3-8 days.

What are the Symptoms?

The initial symptoms of Kyasanur Forest disease include the sudden onset of chills, a fever and headaches. Symptoms may worsen 3-4 days after the initial onset of symptoms and can include muscle pain, vomiting, gastrointestinal distress and bleeding. The infected individual may also experience a low blood pressure, and low platelet, red blood cell and white blood cell counts. Most patients will recover with only 1-2 weeks of symptoms. However, some patients will experience two waves of symptoms, with the second wave of symptoms beginning during the third week after infection. These symptoms include a fever and more severe neurological symptoms (headache, confusion, tremors, vison problems). Kayasanur Forest disease is fatal in only 3-5% of cases.

Preventative Measures

A vaccine is available and is used in areas of India where the disease is commonly found. The vaccine has a 62.4 percent effectiveness rate for individuals who receive 2 doses. For individuals who receive an additional dose, the effectiveness increases to 82.9 percent.

Preventative measures should include: avoiding direct contact with ticks, especially in the dry season, avoiding wooded or rural areas, using insect repellent containing 20 percent or more of DEET and wearing protective clothing to cover exposed skin.


The patient should seek medical care when they suspect that they have been in contact with a tick or animal carrying the virus. The disease is identified by isolating the virus in the blood of the infected individual. There is no specific treatment for Kyasanur Forest disease, however, early contact with medical services, hospitalization and proper care for the patient’s symptoms is recommended.


Where Does It Commonly Occur?

Kyasanur Forest disease is spread by the ticks and animals that are host to the virus, therefore, the disease can be found wherever there are infected hosts. However, the disease is typically limited to the western and central parts of Karnataka State, India, with some recent reports of the virus in other districts of India.