Another Nipah outbreak in India: What do we know about this virus and how to stop it?

September 15, 20234:50 PM ET

By Kamala Thiagarajan

Ari Daniel

The Southern Indian state of Kerala is now battling another deadly outbreak of the Nipah virus, its fourth since 2018. Authorities were alerted to the outbreak after two deaths attributed to the virus. A 49-year-old man named Mohammed Ali, who lived in the village of Maruthonkara, died on August 30, and 40-year-old Mangalatt Haris, who lived in the town of Ayanchery, died on September 11.

On September 13, test results confirmed that both men had died of Nipah. Authorities tested for the virus from routine nose swabs. A combination of flu-like and neurological symptoms — headache, fever, cough, acute respiratory distress and seizures — alerted them to test for the virus.

The virus, first identified among pig farmers in Malaysia in 1999, likely jumped to humans at that time from infected pigs. But there was no human-human transmission noted during the Malaysian outbreaks, says Dr. Thekkumkar Surendran Anish, associate professor for community medicine at the Government Medical College at Manjeri, Kerala, who is leading the state’s surveillance team and who spoke to NPR about the situation.

There are two strains of the virus.

“There is virological evidence that the strain we’re encountering in Kerala is the Bangladeshi strain,” says Anish. This has a high fatality rate of 75% and causes acute respiratory distress, with the higher possibility of human-to-human transmission, he adds.

Meanwhile, health authorities wanted to determine if the cases were related. The one apparent connection, discovered on closed circuit TV footage, is that Haris was visiting a sick relative in a ward in the hospital where Ali was a patient — and the same health worker was identified in both wards. The virus is not airborne but can be spread with contact with body fluids from an infected person or with infected food.

The health worker was not wearing a mask or gloves. “It’s possible that he could have transmitted the disease through contact with surfaces such as counters or the side of the bed,” Anish says.

On the morning of September 15, Anish encountered yet another case — a 39-year-old man who’d been attending to a patient in the adjacent bed when Mohammed Ali was hospitalized. So far, in addition to the two deaths, Kerala has confirmed six active cases of Nipah.

Kerala has a wide variety of bat species; tests of some fruit bats in 2018 showed that they harbored the virus. Samples of bat urine and half-eaten fruit have now been collected from Maruthonkara, the village in Kozhikode, where the first victim lived, and authorities are testing bats in the area for the virus too.

Health authorities in Kozhikode have created 43 containment zones, especially monitoring anyone with a fever as well as the 950 people who were in contact with the two deceased men. The state’s Health Minister Veena George advised the general public to wear masks as a precaution.

“There’s no rationale for masking up, since the Nipah virus does not spread through the air,” says epidemiologist Raman Kutty, research director at the Amala Cancer Institute in Thrissur, Kerala. “Health authorities are just being very cautious,” he says.

They’ve also asked the public to be vigilant for such symptoms as headache, disorientation, fever, cough and seizures. Neighboring states of Karnataka and Tamil Nadu have been asked to stay on high alert for cases as well.

There is no vaccine nor cure for Nipah yet, and supportive care is all that patients can be given.

“The virus has an incubation period of 14-21 days,” says Anish. “Judging from the time of the secondary infections, we’re still in the middle of this outbreak,” he says. And there’s at least one piece of the puzzle that authorities still don’t know — How the patient Ali contracted Nipah in the first place.