Kyasanur Forest Disease: A tick-borne viral illness is spreading in the Western Ghats

As temperatures rise in Karnataka’s Malenadu region, located along the Western Ghats, the residents remain on high alert due to the resurgence of a tick-borne illness endemic to India – Kyasanur Forest Disease (KFD). Locally known as monkey fever or mangana kayile in Kannada, this viral haemorrhagic disease, caused by a Flavivirus in the family of Flaviviridae, carries an estimated fatality rate of 3% to 15%. Dengue, in comparison, kills around 2.6% of the infected, according to an estimate.

The zoonotic disease follows a predictable annual cyclic pattern, emerging during the peak winter months of November and December, reaching its zenith in the summer, and then disappearing completely with the onset of monsoon, only to resurface with varying intensity the following year.

Since January this year, the region has already recorded 12 deaths, and more than 250 positive cases of KFD. The recent demise of a seven-year-old child in Uttara Kannada district due to KFD has heightened concerns.

Highlighting the gravity of the situation, KP Sripal, a Shivamogga-based advocate and a member of the KFD Janajagruthi Okkoota, a civil society group advocating for better accountability and government protection against the disease, notes that this tragic incident marks the first child fatality from the disease in over 30 years.

While we couldn’t verify the claim due to a lack of data, Dr KJ Harshavardhan, deputy director of the government-run Virus Diagnostic Laboratory in Shivamogga, says that a child’s death is a rare occurrence in KFD cases. “Young children do not go into the forest often and they also have better immunity against the virus. This death is a rare one,” he tells Mongabay-India.

Health officials also observe a broader trend wherein KFD cases peak approximately every four or five years, although no official study has been conducted to substantiate this claim.

This trend could potentially be due to the four to five-year immunity the body builds against the virus after an attack, points out Shivamogga resident Darshan Narayan, a scientist with ATREE who has previously worked with the Indian Council of Medical Research and the state health department on the disease. Thus, 2024 holds particular significance, as the local residents and officials report that the last major outbreak in this region occurred in 2019.

A looming threat of deficient rainfall and intense heat, conditions conducive to the proliferation of ticks, provides additional risks this year. “The absence of customary December showers, which typically flush away ticks in their nymph stage – when they are most virulent – has been particularly concerning,” explains Harshavardhan. “While case numbers surged in January and February, there appears to be a promising downward trajectory in March,” he adds.

This Mongabay-India correspondent travelled to Kyasanur and Aralagodu villages, Shivamogga town, and surrounding areas to interview residents and officials at KFD’s hotspots.

Deaths of monkeys

Kyasanur Forest Disease was first identified in 1957 within the Kyasanur forest range, adjacent to a village of the same name in Soraba taluk of Shivamogga. The sudden death of numerous monkeys, followed by fevers in individuals with a history of forest exposure, prompted the then government (the Government of Mysore) to initiate emergency measures such as free distribution of antibiotics for typhoid.

Initially suspected to be typhoid and then yellow fever, subsequent investigations revealed ticks as carriers of an “unknown” virus. Interestingly, despite its name being associated interchangeably with the deadly disease, the village of Kyasanur never reported a death from the disease or has not had any positive KFD cases in the last 25 years, according to the records with Virus Diagnostic Laboratory, as noted by Darshan.

Reflecting on the pivotal days when the disease first emerged, Huchappa, a nonagenarian from Kyasanur village, recounts guiding four forest officers in masks and gloves to the site of the deceased monkeys in the forest. “We spent a fortnight in the forest, returning with the dead monkeys in gunny bags and two live monkeys, caught using sugarcane as bait, in a cage.”

He had a ringside view of the historical event unfolding as no other resident was willing to go into the forest with the officers. Huchappa hazily remembers those monkeys as bili manga or white monkeys, likely referring to Hanuman langurs.

Further laboratory analyses conducted on various tick specimens collected from monkeys, bovines, rodents, and humans, by the former Virus Research Centre in Pune, in collaboration with The Rockefeller Foundation, alongside state public health experts, led to the isolation and coding of the virus as P9605.

Land use change to blame?

During the early stages of detection and research, it was speculated that the virus might have been transmitted via ticks carried by migratory birds. However, the prevailing theory now suggests that the virus is endemic, and likely circulating within the Malenadu forests from an earlier period.

Due to the dense forest cover and minimal human activity within these regions, the virus remained relatively undisturbed. However, with deforestation and significant alterations in land use and ecological dynamics, the virus and its carriers were brought into closer proximity to human populations.

Sixteen tick species – most of them belonging to the genus Haemophysalis – out of 40 species of ticks recorded from KFD affected areas, have been found to be carrying the virus. The virus finds its maintenance and amplification within various host animals, each responding differently to infection.

Humans, acting as dead-end hosts, typically encounter the virus accidentally and do not contribute to its natural cycle. Small mammals such as porcupines, squirrels, and rodents serve as reservoir hosts, crucial for sustaining the virus’s circulation between ticks and reservoir hosts. Although these animals become infected by the virus, they typically do not display symptoms of illness.

In contrast, primates such as Hanuman langurs (Semnopithecus entellus) and bonnet macaques (Macaca radiata), serve as amplifying hosts. The virus undergoes amplification within their bodies, leading to symptomatic infection similar to that seen in humans. The occurrence of monkey deaths serves as a significant indicator, acting as a “sentinel event,” signalling a potential epidemic in the area.

From 1957-1971, the disease was confined to Shivamogga district. It started spreading to the neighbouring district of Uttara Kannada in 1972 and eight years later, in 1980, cases were reported from Chikkamagaluru and from Dakshina Kannada in 1982.

In 2012, the disease was reported from Chamarajanagara district and the Nilgiri district of Tamil Nadu. The following years saw it spread to neighbouring states of Kerala, Goa, and Maharashtra, as well as other districts of Karnataka like Belagavi, Gadag, Mysuru and Hassan.

Fear, stigma

“Lockdown struck our village a year prior to Covid-19,” recalls Chandrakala Ganapathi, a senior citizen of Aralagodu, a village in Sagara taluk, reflecting on the chaos that followed an outbreak of monkey fever in her tight-knit village of just 86 families (as per the 2011 Census). Monkey fever ravaged Aralagodu during the winter months of November and December in 2018, marking one of the most severe outbreaks of KFD in recent memory.

Caught amidst fear and misinformation, the neighbouring villages shunned Aralagodu residents, even prohibiting them from accessing public transportation, as recounted by the villagers.

Chandrakala, who, along with her husband Ganapathi, operates a homestay, shares the stark isolation they endured – neither relatives nor neighbours dared to visit during this period. Farm labourers from neighbouring areas refused to work in Aralagodu, and some of their own workers fell gravely ill with KFD.

Desperate, some residents shuttered their homes and sought refuge in nearby villages. Another resident Shivaraj, who spearheaded relief efforts within the village, says that there was an overwhelming influx of patients at the local public health centre, where four ambulances stood on standby.

Despite its annual cyclic nature, the monkey fever continues to instill fear and perpetuate social stigma, reminiscent of the initial stages of Covid-19 pandemic. Journalists, researchers, or anyone seeking information in the recent outbreak regions of Uttara Kannada and Chikkamagaluru districts are met with hostility and rejection.

During the 2019 outbreak, people believed that the disease was transmitted from human to human. In a 2020 paper addressing social stigma during infectious disease outbreaks, the authors say that stigmatisation and discrimination of individuals can also become barriers to accessing health care and adopting healthy behaviours.

Vaccine withdrawal

Residents of KFD hotspots have other concerns, too. This year, Chandrakala didn’t receive the usual WhatsApp message from the PHC nurse, Pushpa S, reminding her about the preventive vaccination shots.

Additionally, the distribution of Dimethyl phthalate (DMP) oil, which was previously freely provided by the public health centre to prevent tick bites, has also ceased. Some individuals, like plantation worker and KFD survivor Somavathi Mahaveera, received the oil in a brand new bottle without any accompanying explanation.

“The vaccine abruptly stopped early last year. We were anticipating booster doses, but there has been no supply so far,” remarks a perplexed Pushpa. In fact, the department of health and family affairs stopped the manufacturing and distribution of the KFD vaccine, arguably the only defence against the virus, in October 2022, citing potency issues.

A study conducted between 2005 and 2010 by the National Institute of Epidemiology, a sister agency of the National Institute of Virology under the Indian Council for Medical Research, discusses the effectiveness of the vaccine and confirms the loss of potency. The study attributes this decrease in efficacy to potential genetic drifts and variations in newer strains of the virus, as opposed to the strain used for vaccine development in the 1950s.

While Harshavardhan assures that a new vaccine is currently in development at the National Institute of Immunology in Hyderabad and is expected to be available next year, there is unofficial consensus in scientific circles that its completion may require additional time.

At least three other vaccines made abroad have shown effectiveness against the virus. One is commercially available and the other two are awaiting clinical trials.

Impractical preventive measures

In the absence of a vaccine, authorities are urging communities to adhere to preventive measures, which villagers find impractical. “We cannot stop going to plantations or forests because it is our livelihood,” explains Somavathi. She informs us that the tick-repellent DMP oil, though effective, poses challenges due to excessive sweating during outdoor labour activities.

The first one to be infected in Aralagodu in late 2018, Padmavathi, spent over Rs 1 lakh in treatment. She couldn’t access the government’s free medical care for the KFD-infected as she got infected before the outbreak became apparent.

Padmavathi mentions that fatigue has overwhelmed both her and her husband post-infection, making farming difficult. Extreme fatigue is a post-infection condition observed. Additionally, patients experience hair loss, and for women, an infection during menstruation can be fatal.

A 2023 paper that maps the sociodemographic features of the vulnerable population, identifies the poor, landless or smallholders, and households headed by the elderly as particularly susceptible to the disease.

Bheerappa tragically lost both his son and wife, who were labourers at arecanut plantations, to the infection within two days of each other. He recounts that his son and wife were reluctant to get the vaccination.

Apart from vaccine hesitancy, most village residents also shy away from reporting the case in the early stages for fear of having to visit large private hospitals that provide free medical assistance to the KFD infected at the government’s behest.

Changing symptoms and cure

The incubation period of KFD in humans typically spans two to four days. This illness is marked by a sudden onset of high fever and headache, accompanied by a range of symptoms such as body aches, diarrhoea, muscle pain etc., and haemorrhagic manifestations like gum, nose, or gastrointestinal bleeding.

In approximately 10-20% of cases, fever may recur with neurological symptoms such as mental confusion, drowsiness and other related manifestations. Doctors also caution that the viral load plays a critical role in determining the severity of the infection.

Treatment for KFD is currently limited to addressing symptoms. The symptoms, however, are evolving over time. Pushpa says, “Sometimes patients come without the typical headache accompanying fever, which was once considered a hallmark symptom. In some instances, only blood tests confirm KFD.” Unfortunately, by this point, treatment may be initiated too late to effectively combat the infection.

Despite the disease being around for over six decades, KFD’s changing epidemiological profile suggests it to be considered an emerging tropical disease, according to a 2018 study. There is an overwhelming consensus among the general public and experts that the virus strain may be drifting or mutating. “These opinions remain largely hypothetical in the absence of evidence,” says Dr Prashanth N. Srinivas at the Institute of Public Health in Bengaluru who has been studying the disease for a long time.

Darshan highlights the lack of human postmortems since 1992, which could provide valuable insights into histopathological variations resulting from the infection. However, Harshavardhan dismisses the importance of postmortem studies in medical treatment, arguing that since the disease is managed symptomatically, such studies wouldn’t significantly impact medical interventions.

Inaccurate, inadequate data

Missing or faulty data is another serious concern. KFD Janajagruthi Okkoota members accuse the authorities of consistently undercounting cases and conducting inaccurate death audits. The death of 18-year-old Ananya from Hosanagara taluk due to KFD early this year allegedly occurred because the authorities withheld her blood test results. This incident prompted them to send a letter to the prime minister alleging foul play.

Despite 22 reported KFD deaths from Aralagodu alone in 2018-’19, official records indicate zero deaths in 2018 and only 15 deaths in 2019 in Karnataka. Shivaraj highlights that many genuine cases of KFD are rejected based on the victim’s history of alcohol or tobacco use. “The reality is, almost everyone in our village consumes alcohol and smokes tobacco, but not all of them die from KFD,” he points out.

He adds that the monetary compensation ranging from Rs 2 to 2.5 lakh provides significant relief for the victims’ families. The government also offers free medical aid to confirmed KFD cases and inaccurate testing may result in denial of assistance.

Even monkey deaths are often misreported which Darshan says can be detrimental since infected ticks leave a monkey’s dead body when body temperature drops and spread in the nearest forest floor, creating a “hotspot”. “It’s crucial to steer clear of such areas to avoid an infection,” he says.

As KFD-affected regions anxiously await the development of an effective vaccine to alleviate the annual threat and anxiety of potential infections, experts stress the importance of additional measures to curb the spread of the virus. Srinivas emphasises the urgent need to halt rapid land use changes in forested areas, alongside the implementation of enhanced surveillance mechanisms and primary prevention strategies.

Darshan points out that while Kyasanur has not reported any positive cases in decades, the absence of sero-surveillance kits hinders his understanding of why. Srinivas advocates for medico-social audits, akin to death audits, to meticulously analyse cases and identify systemic failures. Experts suggest taking a One Health approach, concentrating on multisectoral collaboration between regional institutions involved in public, animal and environmental health domains.

“It is time for a permanent solution to this,” demands Sripal. KFD Janajagruthi Okkoota has put forward a series of demands to the government. “We are advocating for enhanced health surveillance in KFD-affected regions within the Western Ghats.” Their demands encompass the establishment of another diagnostic laboratory and research centre in Shivamogga, as well as improved reporting of cases and death audits.

This article was first published on Mongabay.