An outbreak of the Nipah virus in India’s eastern state of West Bengal has heightened concerns in China and several Southeast Asian countries, prompting them to tighten health screening operations at airports as millions prepare to travel for the Lunar New Year holiday.
Since December 2025, two confirmed cases of the virus have been reported in West Bengal, India’s health ministry said on Wednesday.
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The ministry did not provide details about the people infected but noted that of a total of 196 contacts linked to the confirmed cases, “all traced contacts have been found asymptomatic and have tested negative”, for the virus.
“The situation is under constant monitoring, and all necessary public health measures are in place,” the ministry added.
A district health officer told Reuters that the two people infected in West Bengal in late December were health workers. Both are being treated at a local hospital, the health officer said.
Is the recent outbreak of the virus a cause for concern?
Here’s what we know:
What is the Nipah virus?
The Nipah virus (NiV) is a zoonotic virus – a disease transmitted from animals such as fruit bats and flying foxes to humans. It can also be transmitted to humans via contaminated food products or directly from person to person.
The virus can be deadly. It typically incubates in the human body for five to 14 days, with symptoms occurring within three to four days.
It causes severe respiratory and neurological disease in humans, progressing from fever and headache to acute encephalitis (brain inflammation) in severe cases, Kaja Abbas, associate professor of infectious disease epidemiology and dynamics at the London School of Hygiene & Tropical Medicine and Nagasaki University, said.
Symptoms can also include convulsions and mental confusion, and patients can fall into a coma within 24 to 48 hours in severe cases.
“The case fatality rate is high, between 40 percent and 75 percent, among people infected with the Nipah virus,” Abbas told Al Jazeera.
However, the virus’s basic reproduction number, which is the expected number of secondary infections stemming from a primary case, is “typically below one”, he said. This suggests the virus spreads in only a limited way via human-to-human transmission and there is a low likelihood of the virus becoming a widespread pandemic.
Where have outbreaks of the Nipah virus occurred before?
The first known outbreak of NiV was reported in 1998 when pig farmers and butchers in Malaysia and Singapore contracted it from infected pigs. At least 250 people were infected, with more than 100 deaths.
In 2014, NiV infections in the Philippines were associated with the slaughter of horses and consumption of infected horse meat.
Since 2001, there have been sporadic but recurring outbreaks in South Asia, particularly in Bangladesh and India.
According to the World Health Organization, outbreaks in Bangladesh have been linked to humans consuming contaminated raw palm sap, having close contact with other people’s secretions and excretions, and caring for infected patients.
According to the WHO, the first cases in India were recorded in West Bengal in 2007 but an earlier outbreak was retrospectively identified in the state’s Siliguri city in 2001. The 2001 Siliguri outbreak occurred in a healthcare setting where 75 percent of cases were of hospital staff or visitors, the WHO said.
Since 2018, dozens of deaths have been reported in India’s Kerala state, which is now regarded as the world’s highest-risk region for the virus.
The reasons for other outbreaks in Indian states are unclear. Some medical experts have suggested outbreaks may have been triggered by human consumption of fruit contaminated by bat saliva or urine, while the Indian Council of Medical Research has suggested that while the virus is primarily spread by physical contact, it may also be airborne.
According to Abbas, there is no clear evidence about the cause of the latest outbreak in West Bengal, which has occurred after decades without outbreaks.
Abbas said the fact that the two confirmed cases are both healthcare workers in the same hospital indicates a potential transmission from an infected but undiagnosed patient to the healthcare workers at the hospital.
Is there a vaccine for the virus?
According to the WHO, there is currently no approved treatment or vaccine available for people infected by the virus or animals carrying the virus.
The University of Oxford has been conducting clinical trials in Bangladesh to test a Nipah virus vaccine and launched the second phase of trials in December 2025.
In the absence of approved vaccines, doctors have been treating patients with antivirals such as Ribavirin. According to the United States government’s Centers for Disease Prevention and Control (CDC), Ribavirin was used to treat a small number of patients in a 1999 Nipah outbreak in Malaysia, but its efficacy in treatment remains unclear.
The CDC has said that the drug Remdesivir could also help prevent Nipah “when given to exposed nonhuman primates”.
The Indian state of Kerala used Remdesivir during a 2023 outbreak which resulted in an improved case fatality rate.
Which countries have announced enhanced screening for Nipah virus?
Thailand, Indonesia, Nepal and Malaysia have all tightened international airport screening.
Thailand’s health ministry told journalists that it has assigned special parking bays for aircraft arriving from Nipah-affected countries, and passengers have been asked to complete health declaration forms before immigration.
Thermal scanners have also been installed at the Suvarnabhumi airport in Bangkok to screen people for fever and other symptoms of the virus.
Malyasia, Indonesia and Nepal have implemented similar measures at their international airports.
What is the best way to prevent the spread of this virus?
On Wednesday, Hong Kong daily The South China Morning Post reported that social media channels in China had been flooded with posts from people expressing concern over the outbreak of the virus in India.
“It’s so scary, especially with the Spring Festival coming up. I don’t want to experience another lockdown,” one social media user said.
“Can’t we temporarily shut the travel channel with India?” another user asked, according to the SCMP.
China’s state broadcaster, CCTV, reported that the country has not recorded any Nipah virus cases so far but warned that there could be risks of imported cases.
According to Abbas, however, the virus is not like the COVID-19 virus which resulted in yearlong lockdowns around the world from 2020.
He said severe cases of the Nipah virus could be managed “through intensive supportive care”.
He added that besides airport health screenings, countries should focus on promoting measures to prevent the virus, like good hygiene, proper ventilation, avoiding crowds, staying home when ill, seeking timely medical advice and maintaining a healthy lifestyle to support immunity.
The WHO has also provided guidelines for controlling the spread of the virus.
In particular, it stated in a 2018 report, “decreasing bat access to date palm sap and other fresh food products” is required.
“Keeping bats away from sap collection sites with protective coverings [such as bamboo sap skirts] may be helpful. Freshly collected date palm juice should be boiled, and fruits should be thoroughly washed and peeled before consumption. Fruits with sign of bat bites should be discarded,” the WHO reported.
It added that people should wear gloves and other protective clothing while handling sick animals or their tissues, and during slaughtering and culling procedures.
To control the spread of the virus in healthcare settings, WHO said, “contact and droplet precautions should be used in addition to standard precautions. In some cases, “airborne precautions” may also be required.
“Close unprotected physical contact with Nipah virus-infected people should be avoided. Regular hand washing should be carried out after caring for or visiting sick people,” the WHO added.
