Urgent warning over deadly ‘brain swelling’ virus amid fears it could spread globally

Airports across Asia have been put on high alert after India confirmed two cases of the deadly Nipah virus in the state of West Bengal over the past month.

Thailand, Nepal and Vietnam are among the countries screening airport arrivals over fears of an wider outbreak of the virus, which can spread from animals to humans and has a high fatality rate.

The Indian health ministry has confirmed two cases in the state of West Bengal since December but said there had been a “timely containment” of the virus.

The government did not give details on the infected patients but said almost 200 close contacts had been tested and no further outbreaks had been detected.

What is the Nipah virus and why is it so deadly?

Nipah virus is primarily transmitted to humans from animals such as pigs and fruit bats, either by direct contact or through their secretions.

It can incubate in the body for a period of four to 14 days. The initial symptoms of the virus are often high fever, nausea, vomiting and respiratory problems, which can then develop into pneumonia. In severe cases it causes a dangerous swelling of the brain that can lead to neurological symptoms such as drowsiness and seizures.

While human to human transmission is low, it is seen by the World Health Organization as a high risk for epidemics because there is no vaccine. It has a high fatality rate of 40% to 75%, far deadlier than Covid-19.

When were previous outbreaks?

The disease was first identified in 1998 among pig farmers in Malaysia, when it killed more than 100 people. It was named after the village where it was discovered.

Since then, outbreaks have been detected almost every year across Asia in countries including India, the Philippines, Singapore and Malaysia. It has routinely emerged in Bangladesh and the first case in India was in 2001 in West Bengal, which borders Bangladesh.

It has been linked to the harvesting of raw date sap in Bangladesh, as fruit bats often live in date palms.

In 2018, at least 17 people died from Nipah virus in the Indian state of Kerala, and two more died in 2023.

How are the authorities handling the latest outbreak?

The Indian health authorities said: “Enhanced surveillance, laboratory testing, and field investigations were undertaken … which ensured timely containment of the cases.”

So far, no more than two cases have been detected since December. “The situation is under constant monitoring and all necessary public health measures are in place,” the Indian health ministry said.

However, other countries have stepped up precautionary screening measures at airports and borders. Thailand, Vietnam and Indonesia have introduced additional screening, including temperature checks and health declarations of passengers arriving from India. Myanmar advised against nonessential travel to West Bengal and China has strengthened disease prevention measures in its border areas.

India said reports of a surge in cases were “speculative and incorrect”.