New Delhi: The death of a 25-year-old nurse in West Bengal Thursday, more than 30 days after she had tested positive for Nipah virus, has raised fresh concerns about the spread of the infectious virus though doctors and health department officials in the state said the woman had died of secondary infection.
The nurse, who tested negative just two days prior, died following a cardiac arrest after weeks in intensive care, state health department officials said. She had remained in a prolonged coma that weakened her immunity and led to a secondary lung infection.
Though she was briefly taken off ventilator support, her condition deteriorated again, and she was put back on ventilatory assistance before her death. N.S. Nigam, West Bengal health secretary, told ThePrint, “The lady died due to cardiac arrest because of prolonged stay in the coronary care unit. There is no further spread of Nipah.”
So far, only two people have tested positive for Nipah virus in the state since December. One has since been discharged after testing negative. The Union health ministry has said that more than 100 close contacts of the nurse, who was first infected with the virus, were traced and have tested negative. Last month, the ministry deployed a national joint outbreak response team to assist the state, and surveillance has since been intensified.
Virologists and medical experts ThePrint spoke to stressed the need to step up surveillance but underlined that there was no need to panic.
Dr Shahid Jameel, a fellow at Green Templeton College, University of Oxford, and visiting professor at Ashoka University, said, “There is no reason to panic but there is every reason to remain vigilant. Doctors in high-risk areas must keep Nipah in mind when patients present with flu-like symptoms and signs of encephalitis. Surveillance and community awareness are our strongest defences.”
This is the third outbreak of Nipah virus in West Bengal since 2001. The first documented outbreak in 2001 was the deadliest recorded in the country, with 66 cases and 45 deaths.
Another outbreak in 2007 claimed five lives. After a gap of more than a decade, the virus resurfaced in Kerala in 2018, where swift containment measures prevented wider spread despite multiple fatalities.
After 2007, this is the first Nipah cluster reported from West Bengal. Meanwhile, neighbouring Bangladesh has reported almost annual outbreaks, and Kerala has faced repeated episodes since 2018.
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What is Nipah virus
Nipah is a zoonotic virus, meaning it jumps from animals to humans, but it can also spread through contaminated food and, in some situations, from person to person. However, there is no evidence of sustained human-to-human transmission. Fruit bats are its natural hosts, and humans, as incidental hosts, have little pre-existing immunity to it.
The virus is regarded as one of the most dangerous pathogens, with outbreaks reporting fatality rates ranging from 40 to 70 per cent, and in some settings, even higher. It is estimated to kill nearly three-quarters of those infected in severe outbreaks.
In 2022, the World Health Organization (WHO) added Nipah to its list of priority pathogens because of its epidemic potential and the absence of specific treatments or vaccines in routine use.
Infection often begins with non-specific symptoms: Fever, headache, muscle pain, vomiting and sore throat. Patients may initially appear stable. However, the disease can rapidly progress to acute encephalitis—inflammation of the brain-causing confusion, seizures, altered consciousness and coma within days. Severe respiratory illness, including pneumonia, has also been observed.
There is currently no widely available antiviral drug proven to cure Nipah, and no licenced vaccine for public use, making supportive care and containment the main tools of response.
Outbreaks in Kerala
Kerala has faced repeated outbreaks of Nipah since 2018. The state’s dense tropical vegetation provides an ideal habitat for fruit bats, which are known carriers of the virus.
Evidence of Nipah virus has been found in bat populations across at least nine states and one Union Territory: Karnataka, Maharashtra, Bihar, Assam, Meghalaya, Tamil Nadu, Goa, Kerala, West Bengal and Puducherry.
However, human spillover has been concentrated largely in Kerala and West Bengal.
Experts attribute this to ecological overlap between bats and humans, as well as specific food practices and animal-human interactions rooted in local culture.
Dr Shahid Jameel said outbreaks are typically linked to exposure to fruit bats, either through consumption of raw date palm sap or fruit contaminated by bat saliva.
“In parts of West Bengal and Bangladesh, drinking fresh, unprocessed palm sap during winter is common. If infected bats feed on the same source, the virus can pass to humans,” he said.
Prevention, not just reactive containment
Despite its severity, Nipah virus does not transmit easily between people, resulting in small, localised outbreaks rather than community-wide transmission.
Professor Gautam Menon, dean of research and professor of physics and biology, Ashoka University, said: “It primarily requires close contact with infected bats, contaminated fruit, or bodily fluids of a patient (to spread).”
That limited transmissibility helps explain why outbreaks in India have remained localised clusters rather than sustained chains of infection. Kerala, in particular, has developed rapid response protocols—early clinical suspicion, aggressive contact tracing and strict isolation—that have prevented wider spread.
“Kerala has done a very good job at this because they’ve done extensive surveillance,” Dr Shaheed Jameel said.
Experts stress that future preparedness must go beyond reactive containment. Professor Menon said ecological and environmental factors play a crucial role in shaping the geography of outbreaks—an area that requires far deeper scientific engagement.
“This is an area where we need to have a much better understanding of the ecological components of health. And disease ecology is an area that we really need to pay attention to in the future because this will tell us what sort of information we need to be collecting,” Professor Menon said.
(Edited by Viny Mishra)
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