Sri Lanka must urgently step up airport screening, hospital surveillance and public health preparedness following a deadly Nipah virus outbreak in India’s West Bengal state, health experts warn, as heavy regional travel begins ahead of the Lunar New Year holidays.

Five confirmed Nipah infections – all among healthcare workers – have been reported from a private hospital in Barasat, near Kolkata, with nearly 100 contacts placed under quarantine.

Several Asian jurisdictions, including Thailand, Nepal, Taiwan and Hong Kong, have already activated enhanced airport health screening protocols.

The warning for Sri Lanka is particularly stark: Nipah virus has already been detected in local flying fox (Mawavula) populations, confirming that the pathogen is present in the country’s wildlife.

“This means Nipah is not a distant threat. The virus exists here, and that changes the entire risk equation,” said Professor Inoka C. Perera, Principal Investigator of the IDEA Laboratory and IDEAnet project at the University of Colombo.

Unlike many previous outbreaks linked to direct bat-to-human transmission, the West Bengal cluster involves human-to-human spread inside a hospital, one of the most dangerous scenarios for outbreak escalation.

Indian health officials say the outbreak began after a patient with severe respiratory symptoms died before Nipah infection was identified. Two nurses who treated the patient in late December later tested positive. Three additional cases – including a doctor – were subsequently confirmed, all linked to the same facility. One nurse remains in critical condition.

Public health experts note that similar hospital-based transmission drove earlier outbreaks, including the 2001 Siliguri incident in India, where three-quarters of infections occurred among hospital staff and visitors.

Nipah virus is among the world’s most lethal zoonotic diseases, with fatality rates ranging from 40% to 75%. It can cause severe respiratory illness and acute encephalitis, often progressing rapidly to coma and death.

There is no approved vaccine and no specific cure. Treatment depends on intensive supportive care, while monoclonal antibodies – available only in limited quantities – must be given immediately after diagnosis. Delayed detection dramatically increases mortality and the risk of onward transmission.

Sri Lanka’s risk is heightened by frequent travel with India and the widespread presence of Pteropus fruit bats. However, scientists say the country has one critical advantage: advance warning.

He told The Island: “We know the virus is circulating in bats, but we have not yet seen human cases. That gives Sri Lanka a rare opportunity to prepare before lives are lost.”

The IDEA Laboratory, working with the Robert Koch Institute of Germany, has established RT-PCR diagnostic capacity for Nipah virus, trained healthcare professionals nationwide, and built a hospital-based surveillance network capable of early detection.

Health experts are calling for immediate measures, including: Health screening at international airports, particularly for arrivals from India, strengthened infection prevention and control protocols in hospitals, heightened surveillance for unexplained fever, respiratory illness and encephalitis, expanded monitoring of flying fox populations, clear public guidance on food safety and early symptom recognition.

The West Bengal outbreak is the first major Nipah incident in the state in nearly 20 years and has emerged near Kolkata, one of India’s most densely populated cities. With the virus capable of spreading person-to-person, experts stress that this is a regional health emergency, not a local anomaly.

Kerala’s experience has shown that swift diagnosis, strict isolation and aggressive contact tracing can contain Nipah outbreaks. Sri Lanka, scientists warn, must act before the first human case appears.

“Every day without a Nipah case is a chance to build defences,” Prof. Perera said. “Waiting until the virus reaches hospitals is a mistake we cannot afford.”

By Ifham Nizam