Two Nipah Cases in West Bengal Spur Airport Screening Across Asia

BARASAT, India — On a foggy January morning in this busy commuter town north of Kolkata, two young nurses lay sedated and ventilated in the intensive care unit of a private hospital. Their abrupt neurological decline had baffled colleagues. Lab results soon offered a chilling explanation: both had been infected with Nipah, a rare but highly lethal virus carried by bats.

By mid-January, India’s central health authorities had confirmed just two cases—both healthcare workers who had treated the same patient. Yet within days, airports from Bangkok to Bali and Singapore to Hong Kong had restarted thermal screening, rolled out health questionnaires and singled out travelers from eastern India for extra checks, evoking the early months of the COVID-19 pandemic.

Officials in New Delhi say the Nipah cluster in West Bengal is contained. No additional infections have been detected among the 196 people identified as close contacts of the two nurses, all of whom tested negative and remained symptom-free during monitoring. Even so, the response across Asia shows how a deadly virus with limited spread can trigger sweeping border measures in a region still shaped by the memory of COVID-19.

“There is no need to panic, but to be on alert,” West Bengal Chief Secretary Nandini Chakraborty told reporters after the cases were confirmed on Jan. 13. “The chief minister herself is closely monitoring the development.”

A two-patient outbreak

The two nurses, both in their mid-20s and originally from districts outside Kolkata, were working at a private facility in Barasat in late December when they developed fever and neurological symptoms, according to state health officials. Their conditions worsened, and they were admitted to the hospital’s critical care unit on Jan. 6 and placed on ventilator support.

On Jan. 11 and 12, the Virus Research and Diagnostic Laboratory at the All India Institute of Medical Sciences (AIIMS) in Kalyani detected markers of Nipah virus in their samples. Confirmatory tests by the National Institute of Virology in Pune followed.

On Jan. 13, the Union Health Ministry announced that the two healthcare workers had tested positive for Nipah virus infection. The United Kingdom Health Security Agency’s Outbreaks Under Monitoring bulletin for the week ending Jan. 18 listed the incident as a new event: two confirmed cases, both healthcare workers in intensive care in West Bengal, receiving the experimental antiviral drug remdesivir.

State officials said the male nurse subsequently tested negative twice on follow-up and began to recover, though he remained under observation. The female nurse remained in critical condition.

The Union Health Ministry deployed a National Joint Outbreak Response Team including experts from the National Centre for Disease Control, the National Institute of Virology, the National Institute of Epidemiology, AIIMS Kalyani and public health and wildlife agencies. The team traced and quarantined 196 contacts, including family members, hospital staff, other patients and visitors linked to the Barasat facility and the nurses’ home districts.

“All 196 contacts identified so far have tested negative for Nipah virus and remain asymptomatic,” a senior central health official said in a briefing carried by Indian media. “Based on the evidence at hand, the situation is under control.”

Confusion over case numbers

In the days after the announcement, some local and national outlets reported that up to five healthcare workers associated with the Barasat hospital had been infected, citing hospital sources and preliminary test results. That prompted a public pushback from the Health Ministry and reference laboratories.

Contrary to reports of a larger cluster, central officials said on Jan. 13 that “only two cases of Nipah virus infection have been confirmed by the National Institute of Virology, Pune, as of now,” according to a statement reported in Indian newspapers. The ministry urged media and the public not to circulate “unverified information” that could trigger “undue panic.”

The discrepancy appears to stem from how cases are classified. Local facilities may label patients with compatible symptoms or preliminary positive tests as “suspected” or “probable” Nipah cases, while national tallies usually count only those confirmed by reference laboratories using standardized molecular tests or serology.

The clarification also reflects the government’s sensitivity to how outbreak numbers can influence travel advisories, trade and public confidence after India’s bruising experience with COVID-19 waves.

A lethal virus with a long memory

Nipah virus, first identified during an outbreak among pig farmers in Malaysia in 1998 and 1999, is carried by fruit bats and can spread to humans through contaminated food, contact with infected animals or close contact with infected people. It can cause illness ranging from mild respiratory symptoms to acute encephalitis—brain inflammation—often leading to coma and death.

The World Health Organization estimates the case-fatality rate between 40% and 75%, depending on the outbreak and quality of clinical care. There is no licensed vaccine or specific antiviral treatment; care is largely supportive, although drugs such as remdesivir have been used experimentally.

Doctors in India have warned that the incubation period—the time between exposure and onset of symptoms—is typically four to 14 days but in some documented cases can be as long as 45 days, complicating contact tracing and international surveillance.

West Bengal is not new to Nipah. In 2001, an outbreak centered in hospitals in Siliguri, near the border with Bangladesh, caused 66 reported cases with a high fatality rate and extensive spread among healthcare workers and visitors. A smaller but highly lethal cluster was reported in Nadia district in 2007. In recent years, the southern state of Kerala has battled repeated Nipah outbreaks, prompting detailed state action plans and bat surveillance.

Public health officials say that history helps explain why even two cases in West Bengal were enough to prompt an immediate, multi-agency response.

Airports switch on the scanners

If the epidemiological footprint of the current cluster remains small, its impact on regional travel has been broad.

Thailand’s Civil Aviation Authority has ordered comprehensive screening of flights arriving from affected parts of India, including West Bengal. Airlines have been instructed to conduct basic health checks before boarding, and in some cases require medical certificates from visibly unwell passengers. At Bangkok’s Suvarnabhumi Airport and other hubs, arriving travelers from India now pass through temperature scanners and must complete health declaration forms.

Officials have framed the measures as precautionary and aimed at reassuring tourists rather than responding to any specific imported case. Thailand has reported no Nipah infections in connection with the West Bengal cluster.

Singapore’s Communicable Diseases Agency said the city-state has not detected any Nipah cases but is “stepping up vigilance” in light of reports from India. Changi Airport has introduced targeted temperature screening for passengers arriving from areas affected by Nipah. Health advisories at points of entry urge recent travelers to seek medical attention promptly if they develop fever, headache or respiratory symptoms.

The Ministry of Manpower has also asked healthcare providers to maintain a “high index of suspicion” for Nipah-like illness among newly arrived migrant workers from South Asia, reflecting lessons from COVID-19 outbreaks in dormitories that house foreign workers.

In Hong Kong, the Centre for Health Protection has advised residents to avoid nonessential travel to West Bengal and Kolkata amid what local officials called a “low but non-negligible” risk of importation. Nipah is classified as a statutorily notifiable disease there, meaning doctors must report suspected cases. Authorities have intensified temperature screening and medical assessments for passengers arriving from India, particularly those who recently visited eastern states.

Malaysia’s Health Ministry has increased surveillance at all international gateways, with a focus on travelers from higher-risk parts of India. Airport operator Malaysia Airports Holdings has urged passengers to wear masks in crowded terminals, practice hand hygiene and seek care if unwell. The country’s last major Nipah outbreak, in 1998 and 1999, killed more than 100 people and devastated pig farming in some regions, leaving a lasting imprint on policy.

Indonesia has tightened health checks at Bali’s I Gusti Ngurah Rai International Airport, a critical hub for the country’s tourism industry. Thermal scanners now monitor both international and domestic arrivals, and symptomatic travelers can be referred to designated hospitals in Denpasar. Local officials have stressed that the steps are “anticipatory” and that Bali remains open to visitors.

Other governments, including Nepal, Vietnam, Myanmar and China, have introduced or strengthened thermal screening and health declarations for some international passengers, according to regional media reports. In Australia, infectious-disease experts have publicly urged tighter border controls in response to Nipah, though federal health authorities say existing protocols are adequate given the limited spread.

As of late January, no country has reported an imported Nipah case linked to the West Bengal cluster.

A rehearsal for the next threat

Public health specialists say the wave of airport measures is as much about politics and public psychology as about reducing transmission risk.

Health agencies acknowledge that temperature screening and questionnaires can miss infected travelers who are asymptomatic or in incubation periods. But they can raise awareness, deter travel by those who are unwell and signal governmental action at a time when voters and tourists are intensely alert to emerging disease threats.

For India, the Barasat cases are a test of hospital infection control and transparent communication. For its neighbors, they offer a low-stakes rehearsal of border health systems built up during COVID-19.

In Barasat, the private hospital where the two nurses fell ill has tightened its own protocols as investigators continue to examine how they were exposed. State officials say surveillance will continue for weeks, given Nipah’s potential for delayed onset.

At the airport departure halls in Kolkata and beyond, travelers now thread past heat-sensitive cameras and health counters that had grown quiet since pandemic restrictions eased. This time, the virus behind the precautions has infected just two people. Governments across Asia are betting that responding early and visibly will make a difference if the next outbreak does not stop there.