Nipah Virus Outbreak: Why the Deadly Infection Has a 40% To 75% Fatality Rate | Explained

New Delhi: India is grappling with a fresh Nipah virus outbreak in West Bengal, prompting heightened surveillance and health screenings at airports across parts of Asia amid concerns about the virus’s high fatality rate and potential for spread.

Health authorities in West Bengal have confirmed two laboratory-confirmed cases of Nipah virus disease since late 2025, with nearly 200 close contacts traced, monitored and tested so far. Officials say no additional confirmed cases have emerged beyond these.

First identified during an outbreak in Malaysia in 1998, Nipah virus is carried by fruit bats of the Pteropus species, also known as flying foxes, which act as natural reservoirs. While the bats do not show symptoms, the virus can spread over to humans either directly or through intermediate hosts, leading to sporadic outbreaks with high mortality.

What Makes Nipah Virus Dangerous

Nipah virus is a zoonotic pathogen, meaning it can spread from animals to humans. Fruit bats of the Pteropus species are the natural reservoir of the virus, and humans can become infected through direct contact with infected animals, consumption of food contaminated by bats, or close contact with infected persons.

Clinically, the virus is notorious for its high fatality rate, which can range from 40 per cent up to as high as 75 per cent depending on the outbreak and healthcare response.  Initial symptoms include fever, headache, muscle pain, sore throat and respiratory discomfort, often resembling a common viral illness.

Nipah virus is particularly dangerous because it attacks vital organs, especially the brain and respiratory system. Infected patients often develop acute encephalitis, an inflammation of the brain, along with severe respiratory illness. The disease can worsen rapidly, with many patients experiencing seizures, altered consciousness, and coma within days of the onset of symptoms.

Another major concern is the absence of a specific antiviral treatment or an approved vaccine. Treatment remains largely supportive, focusing on managing symptoms and preventing complications. The WHO has classified Nipah as a priority pathogen due to its epidemic potential and the absence of effective countermeasures.

How Nipah Virus Spreads

Nipah virus spreads through multiple routes. The most common mode of transmission is animal-to-human, particularly through consumption of food contaminated by fruit bats. Raw date palm sap contaminated with bat saliva or urine has been identified as a major source of infection in several outbreaks in Bangladesh and India. Direct contact with infected animals such as pigs has also been linked to transmission.

Human-to-human transmission has been documented in several outbreaks, including in India. The virus can spread through close contact with an infected person, exposure to bodily fluids such as saliva, blood, or urine, or contact with contaminated surfaces. Transmission in healthcare settings has been reported when adequate infection-control measures were not in place.

Prevention and Containment Efforts

Preventing Nipah virus infection relies on limiting exposure and strengthening surveillance. Health authorities advise avoiding consumption of raw date palm sap and ensuring food is protected from bat contamination. Reducing contact with fruit bats and infected animals, along with maintaining strict hygiene practices, is considered essential.

In response to the West Bengal outbreak, public health teams have conducted enhanced surveillance, laboratory testing and field investigations, including tracing, monitoring and testing of contacts.  Hospital infection-control protocols, such as isolation of suspected cases and strict hygiene measures, are central to preventing further spread.

India has strengthened its disease surveillance and outbreak response mechanisms following past incidents, with health departments remaining on alert to ensure early detection and containment of suspected cases.

ALSO READ: 'I Also Sat in the Third Row. What is the Problem?': Union Minister Pralhad Joshi on R-day Seating Arrangement Row