In March 2015, Raju, a daily-wage labourer from Cheeyambam colony in Kerala’s Wayanad district, got a severe head and body ache after a fishing trip to the Kabini river nearby. “I had seen a dead monkey in the river,” the 33-year-old said. “I did not touch it, but I drank water from the river.”
A few days later, he started vomiting blood. A medical team, including two junior health inspectors and a doctor, tasked with looking into suspected cases of Kyasanur Forest Disease, also known as monkey fever, visited him. They referred him to the nearest government hospital, where he was admitted after a positive test. He spent almost a month in the hospital in critical condition.
“I thank the health department for helping me come back to life,” said Raju.
Kyasanur Forest Disease – named after the forest in Karnataka where it was first detected – is caused by the Kyasanur Forest Disease virus, a member of the Flaviviridae virus family. The disease spreads through the bite of ticks called Haemaphysalis Spinigera. Infected monkeys serve as blood meal for these ticks, which in turn bite humans.
The initial symptoms are chills, fever and headache. As the disease progresses, the infected person experiences severe muscle pains with vomiting, gastrointestinal symptoms and bleeding, accompanied by abnormally low blood pressure and low platelet, red blood cell and white blood cell counts.
Some patients recover in about two weeks. Others relapse into a second bout of fever accompanied by mental disturbance, impaired vision and tremors. The disease is fatal in 2%-10% of cases.
There is no cure. Patients are given supportive therapy such as hydration and measures to prevent bleeding.
The first outbreak
The disease was first detected in the Kyasanur forest area of Karnataka’s Shimoga district in 1957, when it killed 70 people and a large number of monkeys. The disease is considered endemic to the state as well as to Tamil Nadu and Kerala, although there have been findings of Kyasanur Forest Disease antibodies in animals in the Kutch region of Gujarat, parts of West Bengal and in the Andaman and Nicobar Islands. No humans were infected in these regions, though.
The disease resurfaced in Shimoga in 2012 and the following year, it emerged in Wayanad. A positive human case was confirmed in a colony in Noolpuzha panchayat, 32 km east of district headquarters Kalpetta. Another case was detected from the same colony the next year. In both cases, health officials had the infected persons hospitalised in time and they recovered after three weeks.
India has since reported 400-500 cases of the disease among humans every year.
Kyasanur Forest Disease hit Wayanad hard in 2015, infecting 102 people and killing 11, according to the district health department. The forest department, on its part, recorded the death of 400 monkeys.
Officials in both departments are now watching for signs of another outbreak that they think might start by the end of November. “Ticks develop from nymph to larval stage between November and June and the disease spreads during this season,” said Dr Arun Zachariah, assistant forest veterinary officer at the Wayanad Wildlife Sanctuary.
Another outbreak coming?
An increase in the tick population in Wayanad seems to be behind the outbreak fear. Zachariah said scientists were not sure about the reasons for this, but deforestation and rising temperatures as a result of climate could be responsible for the growth in the tick population between 2013 and 2015. Temperatures in the district went up by 5 degrees Celsius in 2015 compared to the year before, according to data from the meteorological department.
Referring to the destruction of forests in Shimoga, blamed in large part for the first outbreak of Kyasanur Forest Disease in 1957, Zachariah said Wayanad was going through an identical phase of reduction in forest cover.
According to a geospatial assessment of forest cover change in the Nilgiri Biosphere Reserve, the Wayanad Wildlife Sanctuary lost more than half of its forest cover between 1920 and 1973.
“Temperature and humidity are on the rise and, hence, the increase in the tick population,” Zachariah said. “Also, the disease spreads when de-forestation gathers momentum.”
He added that another spell of Kyasanur Forest Disease would not just be bad for humans but could sound the death knell for many primates, such as the lion-tailed macaque and the Nilgiri langur, that are already facing extinction.
“It is very difficult to eradicate ticks,” said Dr V Jithesh, the district reproductive and child health officer who is coordinating the health department’s drive against the disease. “So we have to take preventive measures starting from November. We are trying to stop ticks spreading to other areas.”
The authorities are also worried that the virus may have mutated in the last few years.
Zachariah observed differences between the virus that hit Kyasanur in 1957 and the one that spread in Wayanad last year. “Our tests have established that there is a difference of 12% in the protein level in the two viruses,” he said. “We are in the process of classifying it. We suspect that it has mutated.”
He said a possible mutation could render the existing vaccine, developed by the National Institute of Virology in Pune in 1990, ineffective.
However, Jithesh was confident about the vaccine’s effectiveness, saying, The vaccine has 80% efficacy in lab conditions and 65% in the field.”
He spoke of restricting the movement of people and animals as a means of checking the spread of the disease, with the support of officials from the forest and animal husbandry departments. “We will restrict people’s entry into the forest,” said Jithesh.“We will also disinfect dogs and cattle coming from the forest.”
However, such measures may not be welcomed by the indigenous communities the department is trying to protect. “The indigenous people of Wayanad depend on the forest for their livelihood,” said N Badusha, president of the Wayanad Prakruthi Samrakshana Samithi. “Around 12,000 people live inside the Wayand Wildlife Sanctuary, which is spread over 333 square kilometres.”
With the spectre of an outbreak looming, fear has returned to Wayanad, especially Cheeyambam colony, which reported six deaths last year. Raju, a resident, made it through the ordeal, as did his neighbours Kuttan and Bindu. But the survivors complain of recurring health problems.
“I visit the hospital at least four times a month with complaints of headache, vomiting and dizziness,” said 30-year-old Radha, who spent 30 days in hospital last year. “I even had severe hair loss. I think I still have not recovered from the disease.”