Deadly bat-borne virus sparks pandemic fears in Asia as countries bring back Covid-era border controls

A deadly virus outbreak in India has sparked fresh pandemic fears across Asia, with some countries rolling out Covid-era airport screenings to stop it spreading.

The infection is caused by the Nipah virus, a rare but highly dangerous pathogen that can trigger severe breathing problems, seizures and fatal swelling of the brain.

It is watched closely by health officials because it can spread from animals to humans – and in some cases between people – yet there is no approved vaccine or specific drug treatment. 

The latest concern centres on West Bengal, where at least five healthcare workers were infected earlier this month after an outbreak linked to a private hospital.

One patient is reported to be in a critical condition, while others are being treated in hospital.

Around 110 people who came into contact with the infected patients have been quarantined as a precaution.

So far, no cases have been reported outside India – but the response shows just how seriously authorities are treating the risk. 

Nipah remains rare, but experts warn it has the potential to cause devastating illness when it strikes. Here’s what it is, how it spreads, and whether the outbreak is likely to escalate.

What is Nipah virus? 

Nipah is a zoonotic infection, meaning it can pass from animals to humans – most notably linked to fruit bats, and in some outbreaks pigs.

It’s a virus that worries health officials because it can hit fast and hard, causing anything from no symptoms at all to a sudden, severe illness that attacks the lungs and the brain.

In milder cases, people may only feel flu-like symptoms – but in severe cases it can trigger acute respiratory distress, seizures and encephalitis, a dangerous swelling of the brain that can be fatal.

Another reason it sets alarm bells ringing is that it has been shown to spread person-to-person, particularly among family members and caregivers, making strict infection control crucial when cases are detected.

Health authorities monitor Nipah due to its outbreak potential – and because its death rate in confirmed cases is unusually high, with fatality estimates ranging from 40 to 75 per cent depending on the outbreak and quality of clinical care. 

Why are authorities suddenly screening for it at airports?

Airport checks have been stepped up after cases were detected in West Bengal, with the outbreak linked to healthcare settings where viruses can spread quickly if not contained.

Thailand has started screening arrivals at international airports receiving flights from the region, while Nepal has introduced checks at Kathmandu airport and at land border points with India. 

Taiwan has also proposed classifying Nipah as a high-risk emerging infection under its disease control system.

While measures like these can look dramatic, officials are essentially trying to spot illness early and block any chance of infections slipping across borders.

Airport staff said to be looking for obvious signs of illness, such as a high temperature, and flagging up passengers who have recently travelled from an affected area or report symptoms that could fit an early Nipah infection.

Health declaration forms, mandatory temperature checks and full body heat scanners are the main method of doing this.  

Anyone who appears unwell can then be pulled aside for further medical assessment, with health authorities able to trace contacts more quickly if an infection is suspected.

How does it spread?

Nipah can spread from animals to humans, and it can also be transmitted through contaminated food or direct person-to-person contact.

During the first recognised outbreak in Malaysia in the late 1990s, which also affected Singapore, most human infections were linked to contact with sick pigs or their contaminated tissue, with transmission thought to have occurred through unprotected exposure to secretions from infected animals.

In later outbreaks in Bangladesh and India, researchers believe a key source of infection was consumption of fruit or fruit products contaminated by fruit bats, including raw date palm juice tainted with infected urine or saliva.

Human-to-human transmission has also been reported, particularly among family members and caregivers of infected patients. 

Preliminary investigations suggest the healthcare workers in India caught the deadly virus while treating a patient with severe respiratory symptoms who died before testing could be carried out, according to sources at the hospital.

‘The most likely source of infection is a patient who had been admitted to the same hospital previously. That individual is being treated as the suspected index case, and investigated,’ a health official involved surveillance efforts told The Telegraph.  

Health authorities in Taiwan are now considering listing the virus as a Category 5 disease – a rare or emerging infection with major public health risks, that require immediate reporting and special control measures.

What are the symptoms?

Nipah can begin with symptoms that look like a bad flu or stomach bug, including fever, headaches, muscle aches, vomiting and a sore throat.

In some people, it escalates into something far more serious, with dizziness, drowsiness, confusion and neurological signs that point to acute encephalitis – dangerous inflammation of the brain. Severe cases can involve seizures and rapid deterioration, sometimes progressing to coma within 24 to 48 hours.

Some patients also develop atypical pneumonia and severe breathing problems, including acute respiratory distress.

The incubation period is usually four to 14 days, but it can sometimes be much longer. In rare instances, an incubation period of up to 45 days has been reported.

How deadly is it?

Nipah is known for its high fatality rate. The estimated case fatality rate is 40 to 75 per cent, though this varies between outbreaks depending on how quickly patients are diagnosed and how strong clinical care and surveillance are in affected areas. 

In the worst cases, Nipah can be a rapid and brutal illness because it can cause severe inflammation of the brain (encephalitis) and acute respiratory failure.

Case descriptions from past outbreaks suggest some patients deteriorate from what looks like a standard viral illness – fever, aches, vomiting – into confusion, extreme drowsiness and seizures, before slipping into coma within 24 to 48 hours. 

Others develop severe breathing problems, including pneumonia and acute respiratory distress, which can be fatal without intensive supportive care.

However many people who survive make a full recovery – but the virus is feared because severe cases can worsen dramatically, and some survivors are left with long-term neurological damage. 

There have also been reports of relapse in a small number of cases.

Is there a vaccine or treatment?

There are currently no approved vaccines or drugs that specifically target Nipah virus infection.

Instead, doctors rely on intensive supportive care, treating the most dangerous respiratory and neurological complications as they arise.