On Friday (January 30), the WHO said the Nipah outbreak in India has a « low risk » of spreading and that there is no need for travel or trade restrictions, following the country’s report of two cases. This comes after several Asian countries stepped up checks on people arriving in their territories for signs of the virus. In an update shared on its website, the global health agency said that there is no evidence of increased human-to-human transmission and that the “national, regional, and global risk remains low”.
The two cases were reported in the North 24 Parganas district of West Bengal. WHO said the cases are limited to the district and that no travel was reported while the patients were showing symptoms.
“The likelihood of spread to other Indian states or internationally is considered low,” it said.
This has not stopped several Asian countries from implementing precautionary health checks for travellers arriving from India. Thailand has tightened screening at major airports, including Suvarnabhumi, Don Mueang and Phuket. They have also assigned designated parking bays for aircraft arriving from affected areas. Singapore and Hong Kong have set up temperature screening at airports for flights from affected regions. Pakistan is now also requiring thermal screening and a 21-day transit history for all incoming travellers.
The Nipah virus (NiV) was first identified in the late 1990s and has since caused periodic outbreaks across South and South East Asia. First identified in Malaysia in 1998 during a major outbreak among pig farmers, the Nipah virus subsequently emerged in Bangladesh and India in 2001, where it began causing nearly annual clusters linked to fruit bats. Over the last decade, the virus has repeatedly surfaced in Kerala, including in 2018 and 2025, before returning to West Bengal in January for the first time in nearly two decades.
Nipah virus infection typically begins with flu-like symptoms that appear between four and 14 days after exposure. Patients often experience a sudden onset of high fever, severe headache, muscle pain (myalgia) and a sore throat. In many cases, the virus also attacks the respiratory system, leading to a persistent cough and, in severe cases, acute respiratory distress or pneumonia.
The most critical and dangerous phase occurs when the virus invades the central nervous system, causing encephalitis (inflammation of the brain). This stage is marked by drowsiness, disorientation, and mental confusion, which can rapidly escalate to seizures and a coma within 24 to 48 hours. Even for those who survive, roughly 20% are left with long-term neurological consequences, such as persistent convulsions or personality changes.
The case fatality rate (CFR) for Nipah virus is alarmingly high, typically estimated by the WHO to be between 40% and 75%. However, Nipah fatality rates vary significantly by virus strain, with the « Bangladesh/India » strain (NiV-B) often proving more lethal and transmissible than the original Malaysian strain. Additionally, a patient’s survival depends heavily on the speed of diagnosis and the availability of advanced supportive care, as there is currently no specific cure or vaccine.
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