Recent reports of a rare but highly dangerous virus, known as the Nipah virus, have drawn widespread attention following the confirmation of new cases in India.
The development has prompted health authorities in several Asian countries, including Thailand, Singapore, Malaysia and Hong Kong, to heighten surveillance, tighten airport screening and activate cross-border disease monitoring systems.
The Nipah virus belongs to a group of pathogens called henipaviruses and is classified as a zoonotic disease, meaning it can be transmitted from animals to humans.
The virus derives its name from Sungai Nipah, a village in Malaysia where it was first identified during an outbreak in the late 1990s.
Fruit bats, particularly those belonging to the Pteropus species found across parts of Asia and Australia, are recognised as the natural reservoir of the virus.
Transmission to humans can occur through direct contact with infected animals such as bats, pigs or horses, or through the consumption of fruits and fruit products, including raw date palm sap, contaminated by infected bats.
Health experts note that Nipah virus can also spread between humans through close physical contact, especially in healthcare settings with inadequate infection prevention measures.
The risk of person-to-person transmission increases in situations involving overcrowding, poor ventilation and lapses in protective practices such as hand hygiene, surface disinfection and the proper use of personal protective equipment.
According to the World Health Organisation, symptoms typically appear within three to 14 days after infection, although incubation periods of up to 45 days have been documented in rare cases.
Early symptoms often include fever, headache, cough, breathing difficulties and altered mental status such as confusion or drowsiness.
Other reported signs include fatigue, chills, dizziness, vomiting and diarrhoea, with some patients progressing rapidly to severe neurological complications.
In advanced cases, the virus can cause inflammation of the brain, known as encephalitis, which frequently leads to coma within five to seven days of symptom onset.
Medical studies indicate that approximately two-thirds of infected individuals experience severe disease progression, while long-term neurological complications have been reported in about one in five survivors.
The United States Centres for Disease Control and Prevention classifies Nipah virus as a biosafety level four pathogen, placing it among the world’s most hazardous infectious agents.
This classification reflects the virus’s high fatality rate, which can reach up to 75 per cent, its ability to spread between humans and the absence of approved vaccines or targeted antiviral treatments.
Currently, there is no specific cure for Nipah virus infection, and treatment is largely supportive, focusing on managing symptoms and preventing complications.
The WHO states that early diagnosis improves outcomes by enabling prompt supportive care, including oxygen therapy, hydration, nutritional support and intensive monitoring.
Severe cases may require advanced interventions such as mechanical ventilation, dialysis or treatment for brain swelling and secondary infections.
Although several experimental vaccines for animals are under development, they remain in early research stages and are not yet licensed for widespread use.
Historically, the Nipah virus was first identified in 1998 during an outbreak among pig farmers in Malaysia, resulting in nearly 300 human cases and over 100 deaths.
The following year, Singapore recorded cases linked to the importation of infected pigs, after which both countries implemented strict control measures that halted further outbreaks.
Since 2001, repeated outbreaks have been reported in Bangladesh and India, with Bangladesh recording near-annual cases largely linked to contaminated date palm sap.
In 2014, the Philippines reported an outbreak associated with horse exposure, although no subsequent cases have been recorded there.
India has experienced periodic Nipah outbreaks in different regions over the years, including the most recent cases confirmed in late 2026.
Indian health authorities have reported two confirmed infections detected in West Bengal, involving healthcare workers currently receiving treatment under isolation.
The federal ministry of health said 196 contacts linked to the cases have been traced, tested and placed under observation, with no additional infections identified so far.
“The situation is under constant monitoring and all necessary public health measures are in place,” the ministry said in a statement.
In response, neighbouring countries have introduced precautionary screening measures at airports and border points, including temperature checks and health declaration requirements for travellers arriving from India.
Myanmar has advised against nonessential travel to West Bengal, while China has strengthened disease surveillance in its border regions.
The WHO has assessed the overall risk of international spread from the reported cases as low and has not recommended travel or trade restrictions.
“The WHO considers the risk of further spread of infection from these two cases low,” the organisation said, adding that there is no evidence of increased human-to-human transmission.
The global health body also noted that India has the technical capacity and public health infrastructure to contain such outbreaks effectively.