Kerala’s health machinery is pulling out all stops to keep Nipah under control
Face masks have returned to the quiet residential area of Melevaram near Farook College in Kozhikode. From the casual scooter rider to the medical professionals huddled outside a family medical center, everyone wears them.
The pervasive sense is not fear or anxiety, but caution. The reason is not hard to miss; a 43-year-old resident of the locality was diagnosed with a fatal Nipah infection.
But Abdul Azeez, one of his neighbors, doesn’t seem too concerned. “The doctors told us that the infection is not spreading as fast as COVID-19. They visit the place to monitor the situation every day. But yes, most of us wear face masks when we go out as a precaution,” he says.
The infected person has been on ventilator support at Government Medical College Hospital (MCH), Kozhikode since June 10. His close family members are already under home quarantine, says Venugopal, a relative staying nearby.
Contacts under supervision
“All his close people are now under observation. If any of them show symptoms of infection, laboratory tests are carried out. So far, they have all tested negative for the virus. Hopefully, he will survive this ordeal,” he adds.
However, health workers under Ramanattukara municipality, under which the locality falls, are not taking any chances. A preliminary survey of about 300 houses in the area has already been completed. Rajul Koyadeen, a doctor attached to the local body, says a fever survey is underway to see if any of the residents had symptoms related to the deadly zoonotic disease. The Health Department is also coordinating with the Animal Husbandry and Forestry Departments under the ‘One Health’ initiative, taking steps to curb it. A team from the Indian Council of Medical Research also visited the area.
Mortality 75%
Their wariness has its background. Nipah, the virus that causes the infection, has a mortality rate of up to 75%. It is usually transmitted from infected bats and other animals to humans, and can also be transmitted directly between humans. The Pteropus species are the natural hosts of the virus. Nipah is also one of the pathogens on the list of “epidemic threats requiring immediate action” by the World Health Organization (WHO) in the research and development plan.
Medical waste clearance from Nipah Isolation Ward at Government Medical College Hospital, Kozhikode. | Photo credit: K. Ragesh
For the record, this is the fourth time that Kozhikode has reported a Nipah episode. The first official case of Nipah in Kerala was from there in 2018. Till 2025, 10 episodes of infection have been recorded in the state and so far 38 cases and 28 deaths. After 2018, there was a single case in 2021 and an outbreak in 2023 in Kozhikode. Malappuram, Palakkad and Ernakulam are the other districts from which cases have been reported.
TS Anish, nodal officer of the state government’s Nipah Research and Resiliency Center Kerala One, Kozhikode, highlights some of the patterns that have emerged from the recurring cases of infection in the state. The virus was found to be active in Kerala from April to September. The most cases were in September so far.
“The fruiting season in the state is around April. Bats forage during this period. Since bats are natural reservoirs of the virus, transmission of the infection through fruits can occur in this month,” he notes. Bat breeding season is also in April-May and then in September. “They become more aggressive and virus shedding – the release of infectious particles into the environment – increases during these months if they are disturbed,” he explains.
Another pattern is the emergence of Perinthalmanna in Malappuram and the city of Kozhikode as the two most important places in the Nipah calendar. The presence of corporate hospitals and government tertiary care hospitals in this region, where most of the patients are admitted, is the reason for the scenario, he claims.
“Most of the cases were in the six districts that are south of Kannur. The infection is also spreading south from Kozhikode to Malappuram and then to Palakkad and Thrissur, possibly due to movement of bats from one place to another,” notes Dr Anish.
A nationwide survey conducted by the National Institute of Virology, Pune, a few years ago revealed antibodies against the Nipah virus in bats in nine states, including Kerala. A 2021 study revealed the presence of the virus in bats in “many counties” across the state. As most of the bats are found close to human habitats, there is an ever-present threat of spillover, according to another study by the wildlife biology department of the Kerala Forest Research Institute. However, Nipah virus was never isolated in any fruit samples collected and tested during the outbreaks. Its transmission to humans through fruit bitten by bats remains a scientific possibility. However, each episode of infection comes with doubts about its recurrence in Kerala, especially in Kozhikode.
Also in many other states
AS Anoop Kumar, a critical care specialist at a private hospital in Kozhikode, who played a key role in detecting Nipah cases in 2018, 2023, 2024 and this year, says the virus is present in many other states across the country. But similar cases often go undiagnosed there because patients with a high index of clinical suspicion in those places may not be screened for Nipah. “In Kerala, especially in Kozhikode, a group of doctors and health workers are familiar with its clinical features. Hence, such patients are screened regularly because of our experience with the 2018 outbreak,” he says.
Dr. Anoop Kumar also notes that the current patient, who was initially admitted to a private hospital, had no fever apart from the initial period. “He had low sodium and loss of consciousness. The radiologist reported the MRI findings as septic embolism or changes in the brain after infection in the blood. We suspected Nipah because we are used to such patients. According to the clinical screening criteria for Nipah including his history and clinical, radiological and laboratory features, his score was very high,” says Dr. Anoop Kumar.
Since most of the Nipah cases were suspected first in private hospitals and then handed over to the public health system, there is also a demand to strengthen the surveillance system in government hospitals as well.
A. Althaf, Professor of Community Medicine, Government Medical College Hospital, Thiruvananthapuram, points out that recurrent cases of Nipah in symptomatic patients are also a sign of the need for an “active surveillance” system. He says if patients with acute encephalitis syndrome (AES) and acute respiratory distress syndrome (ARDS) are subjected to Nipah-specific tests, more cases could be detected.
Preventive examination
“Currently, the system only responds to the infection after it is detected. If preventive examination, also called active surveillance, is implemented, it can lead to more cases. In the first phase, it can be implemented in Kozhikode and Malappuram districts, from where most such cases are reported so far,” he suggests.
Health department data shows that in 2023, 56 cases of AES and 22 deaths were reported in Kerala. The next year, the number of cases increased to 122 and there were 37 deaths. In 2025, there were 172 cases and 20 deaths. So far this year, there have been 62 cases and 12 deaths.
Dr. Althaf says most of these patients were from the northern regions of Kerala. Japanese encephalitis, West Nile fever, rabies infection and Nipah can lead to AES. “There is a possibility that at least some of the AES cases are Nipah infections in districts where it is frequently reported,” he feels.
Dr. Anoop Kumar says that detecting Nipah patients in the initial period can be difficult as their clinical features are similar to some other diseases. However, screening patients with AES and ARDS will go a long way in detecting more cases, he says. Dr. Althaf and Dr. Anoop Kumar suggests cost effective tests like TrueNat instead of RT-PCR tests.
“Thanks to this, more scientific information can be made available about the mode of transmission of the infection, the nature of its spread and preventive steps. If the infection is diagnosed early, effective treatment can be provided and the patient can be saved,” notes Dr. Althaf.
Political controversy
Meanwhile, a political controversy has also erupted with the opposition claiming there were mistakes in the austerity measures. The sudden transfer of KJ Reena, Acting Director of Health Services, for allegedly not officially sharing the laboratory results of an infected person from the National Institute of Virology, Pune, to Health Minister K Muraleedharan has also sparked controversy.
However, Muraleedharan says every effort is being made to save the patient’s life. “He was admitted to the hospital in a critical condition. His blood pressure and cholesterol levels seem to be fluctuating. Remdesivir, an antiviral currently unavailable in India, has been purchased from Bahrain. Monoclonal antibodies and ribavirin, another antiviral, are being administered along with it,” he says.
There is maximum vigilance and precautionary measures to prevent further transmission of infection in healthcare facilities or among close contacts of an infected person.
The challenge posed by Nipah could be formidable, but the health system in Kerala is doing its best to overcome the crisis with proven methods.