Mint Explainer | Understanding the Nipah virus threat in West Bengal and what the government is doing to contain it

A National Joint Outbreak Response Team has been deployed to prevent the spread of the virus. Given the high fatality rate and the absence of a licensed vaccine, understanding this threat is critical for public safety.

What is the Nipah virus and why is it dangerous?

The Nipah virus is a zoonotic virus, one that spreads from animals to humans. It is considered a major public health threat because of its high fatality rate, which typically ranges from 40% to 75%, and, in some cases, exceeds 90%. The virus causes a rapid, terrifying progression from mild flu-like symptoms to acute respiratory distress and fatal encephalitis, which is a severe inflammation of the brain that can lead to a coma within 24 to 48 hours.

Nipah virus is a major public health threat due to its high fatality rate—typically 40% to 75%, and in some cases over 90%.

How does the virus spread from animals to humans and between people?

The natural reservoirs of the virus are fruit bats, specifically the Pteropus species or "flying foxes." Humans typically catch the virus by consuming food contaminated with bat secretions, such as drinking raw date palm sap or eating fruits bitten by bats.

Once a human is infected, the virus can spread to others through close contact with bodily fluids—blood, urine, or saliva. This transmission is particularly dangerous in hospital settings, where healthcare workers may be exposed to respiratory droplets or secretions while providing care without personal protective equipment.

What is the history of the virus in India and abroad?

The Nipah virus was first identified in Malaysia in 1998, and it has emerged as a recurring zoonotic threat in India and Bangladesh.

In India, the virus first appeared in Siliguri in West Bengal in 2001, where 66 people were affected primarily through hospital-based transmission. A second outbreak occurred in the Nadia district of West Bengal in 2007.

Since 2018, there have been repeated outbreaks in Kerala, with one of the deadliest occurring in 2018 resulting in 17 deaths.

These patterns suggest that while the virus is geographically constrained, the "spillover" from bats to humans is becoming more frequent due to environmental changes.

What does the Indian Council of Medical Research (ICMR) say about potential treatments?

According to ICMR, India is working to develop indigenous countermeasures to infections by the virus as there is currently no approved vaccine or antiviral treatment. The most promising candidate is the m102.4 monoclonal antibody that prevents the virus from entering cells. The antibody has shown strong protection in animal models and was found safe in Phase 1 clinical trials.

While definitive human efficacy data is still being gathered, the antibody has been used under compassionate use protocols in Australia and was made available to Kerala during recent outbreaks. ICMR is looking for Indian companies to make these antibodies indigenously.

Experts said the symptoms of Nipah infection can initially look like a routine viral fever, but neurological signs or breathing difficulty are red flags.

“Samples must be handled with extreme caution. RT-PCR testing and close coordination with reference labs are essential to confirm cases without delay," said Dr. Aakaar Kapoor, founder and designated partner of City Imaging & Clinical Labs, a medical diagnostics company in New Delhi.

What is the government doing to combat the virus?

The government has activated the PHEOC and deployed experts from the National Institute of Virology and the National Centre for Disease Control to conduct rigorous contact tracing.

Current efforts focus on early diagnosis, strict isolation and public awareness, reflecting the lessons learned from past sudden escalations.

In the past, the government contained outbreaks through aggressive "test-track-treat" strategies and by upgrading safety protocols at medical colleges, providing protective gear to professionals and implementing stringent infection control.

Why is the West Bengal case of concern?

The situation in West Bengal has sparked high-level alerts because the suspected patients are healthcare workers. This echoes the 2001 Siliguri outbreak, where 75% of the 66 cases were hospital-acquired.

When the virus spreads in a clinical environment, it necessitates the immediate activation of biosafety level-4 (BSL-4) protocols and the strict isolation of primary contacts to prevent a wider outbreak. BSL-4 is the highest level of biological containment, reserved for work with extremely dangerous and often fatal pathogens for which there are no known vaccines or treatments.

“Treatment remains largely supportive, focusing on symptom management and preventing complications. Vigilance, early diagnosis, strict isolation, and public awareness remain the strongest tools to prevent a limited outbreak from escalating into a larger health crisis," said Dr. Pranjit Bhowmik, chairman-internal medicine (Unit-I) of the Faridabad-based Asian Institute of Medical Sciences.