Health authorities in West Bengal confirmed five cases of the deadly Nipah virus this month, prompting urgent containment measures and triggering heightened surveillance across neighbouring Asian countries.
The outbreak, centred around Barasat near Kolkata, has affected five healthcare workers at a private hospital. Three new infections emerged this week, adding to two nurses who tested positive earlier. Nearly 100 people have been placed under home quarantine, while authorities have tested approximately 180 individuals as part of contact tracing efforts. One patient remains in critical condition, according to Narayan Swaroop Nigam, principal secretary of the health and family welfare department in West Bengal.
The outbreak has prompted swift action from neighbouring countries. Thailand’s Ministry of Public Health began screening air passengers arriving from India at Suvarnabhumi and Don Mueang airports, focusing on travellers from West Bengal. Nepal has heightened nationwide alertness, with health screenings initiated at Tribhuvan International Airport and major border points. “We have intensified surveillance particularly at border points in Koshi Province,” said Prakash Budhathoki, spokesperson for the Nepal Ministry of Health and Population.
China added Nipah virus to its updated list of monitored infectious diseases on 30 December 2024. Chinese medical expert Zhuang Shilihe noted that while the virus is highly pathogenic, “its transmission capacity remains quite limited” based on observations during previous sporadic regional outbreaks worldwide.
In response to the outbreak, teams from the National Institute of Medical Research have begun conducting RT-PCR tests on bats across West Bengal. Blood and swab samples were collected from bats at Kolkata’s Alipore Zoological Garden. State Chief Wildlife Warden Sandeep Sundriyal confirmed that “catching bats require prior permission from the Forest department. The health department sought approval, which we granted.” Samples have also been collected from bat populations in Madhyamgram, Barasat and Basirhat areas.
Nipah virus is classified as a priority pathogen by the World Health Organisation owing to its epidemic potential. The virus is mainly carried by fruit bats of the Pteropus species, creating a constant risk of spillover to humans through contaminated food or direct contact. It can also transmit through contact with a patient’s secretions or excreta, carrying a risk of nosocomial infection.
According to WHO, case fatality rates are estimated at between 40 per cent and 75 per cent. Initial symptoms include fever, headache, muscle aches, sore throat and cough. However, neurological warning signs such as confusion, excessive sleepiness, seizures and reduced consciousness indicate the virus should be treated as a medical emergency.
Currently, there are no vaccines or specific antiviral treatments available for Nipah virus. Treatment focuses on supportive care. During a 2023 outbreak in Kerala, early application of the antiviral Remdesivir resulted in an improved case fatality rate.
This outbreak marks West Bengal’s first significant Nipah virus incident in nearly two decades. Unlike previous outbreaks concentrated in Kerala, which has reported cases regularly since 2018, this event has unfolded in India’s eastern region.
The Ministry of Health posted guidance regarding prevention measures, including washing fruits before consumption, drinking chlorinated and boiled water, and wearing protective clothing when handling animals. India’s National Centre for Disease Control confirmed the outbreak but stated it is “not major”. Airports across Asia have implemented protocols similar to those used during the coronavirus pandemic, conducting additional screening for travellers with symptoms compatible with Nipah virus infection.
