Kyasanur Forest Disease: A Potentially Fatal Viral Disease in India

Kyasanur Forest Disease is also called “Monkey fever”. Kyasanur Forest Disease Virus (KFDV) was first isolated during an outbreak of the febrile disease in 1957 in people living in the Kyasanur forest area of the Shimoga district in the Karnataka (then Mysore) state of India. Virologists confirmed that there were several cases of severe febrile illness in residents of villages close to forested areas where dead monkeys had been found.

Serological evidence indicate that the novel illness was caused by a virus related to the Russian spring-summer encephalitis (RSSE) complex of arboviruses, now known as the tick-borne encephalitis (TBE) serocomplex of flaviviruses, which are typically associated with a neurologic syndrome. The identification of KFDV provided the first conclusive evidence that a tick-borne flavivirus was circulating in India.

In February 2012, there was an outbreak of Kyasanur Forest disease (KFD) in Tirhahalli and Hosanager taluks in the Shimoga district of India, with 176 suspected and 38 confirmed cases. It has been estimated an average of 400-500 cases of KFD occur every year in India. Similar diseases have also been reported in countries like China and Saudi Arabia since 1995. The pathogenic mechanism of the disease and the host response to infection remains unclear. The mortality rate is estimated at 3–10 percent in KFDV cases.

What is KFDV?

The KFDV virus belongs to the Flaviviridae family as a single-stranded positive RNA virus.

Transmission

A tick, Credits: canva

It can occur after a tick bite or contact with an infected animal, most notably a sick or recently dead monkey. No transmission was confirmed from person to person. Large animals like goats, cows and sheep can get infected by KFD, but are of limited importance in disease transmission. These animals provide the blood meal for ticks and infected animals will infect other ticks, however KFDV is exceedingly rarely transmitted to people from these greater animals.

Signs and Symptoms of Kyasanur Forest Disease

A man checking his nose for bleeding, Credits: canva

The incubation period of the illness is 3 to 8 days. The symptoms begin suddenly with chills, fever, and frontal headache. Patients may experience extreme muscle pain with vomiting and bleeding from the nasal cavity, the mouth, the gingiva, and in some cases the gastrointestinal tract after 3 to 4 days of initial symptoms.

An abnormally elevated blood pressure and low platelet, red blood cells, and white blood cell counts are also possible in patients. Some patients recover without complications after 1-2 weeks of symptoms. A number of patients (10-20 percent) who develop a second wave of symptoms at the start of the 3rd week seem biphasic to the condition. These effects include fiber and neurological symptoms, including extreme headache, emotional upheaval, tremors and vision deficits.

Diagnosis

The early stages of illness are identified by performing a molecular test by PCR. Serological testing is performed by enzyme-linked immunosorbent serologic assay (ELISA).

Treatment

KFD is not eligible for specific treatment. It is critical to get early hospitalization to support treatment. Supportive care requires hydration maintenance and the standard precautions for bleeding disorder patients. Doctors will take precautionary measures to prevent bleeding and neurological symptoms from aggravating.

Prevention

A KFD vaccine is used in India’s endemic regions. Such precautionary steps require the use of protective clothing in endemic areas.

The other preventive measures include:

1. Identifying tick hotspots using regular tick mapping and surveillance techniques can help us kill them at the roots.

2. Spraying insecticides up to 50 meters around the spot where monkey death was detected.