Following the confirmation of two Nipah virus cases in West Bengal, India, airports throughout Asia are on heightened alert. This move aims to curb the spread of the virus, known for its high mortality rate and ability to transmit from animals to humans.

Countries including Thailand, Nepal, and Vietnam have initiated screening procedures for incoming travelers as a precautionary measure against a potential outbreak. This virus, which poses significant health risks, necessitates vigilant monitoring.

The Indian health ministry has reported these two cases since December, emphasizing that swift action has been taken to contain the virus effectively.

Details about the infected individuals remain undisclosed, but authorities have tested nearly 200 people who had close contact with them. Fortunately, no additional cases have emerged.

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

Nipah virus transmission to humans commonly occurs through direct contact with infected animals such as pigs and fruit bats, or through exposure to their secretions.

The virus can remain dormant in the human body for four to 14 days. Early symptoms typically include a high fever, nausea, vomiting, and respiratory issues, which can escalate to pneumonia. In severe instances, it may cause brain inflammation, leading to neurological complications like drowsiness and seizures.

It is highly contagious between humans and 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 latest outbreak is significant as these are the first cases detected in West Bengal since 2007.

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”.