There are currently no approved vaccines or treatments, although a number of candidates are being tested
Two cases of the deadly Nipah virus in India have prompted authorities in Thailand and Malaysia to step up airport screening to prevent the spread of the infection.
Pakistan also subsequently ordered strict and enhanced health surveillance at all entry points following regional alerts.
But what is the Nipah virus and how worried should people be?
What is Nipah virus?
Nipah is a rare viral infection that is largely spread from infected animals, mainly fruit bats, to humans. It can be asymptomatic, but it is often very dangerous, with a fatality rate of 40% to 75%, depending on the capacity of the local health system for detection and management, says the World Health Organization (WHO).
But while it can also spread from person to person, it doesn’t do this easily, and outbreaks are usually small and fairly contained, according to experts and the European Center for Disease Prevention and Control. Candidate vaccines are in development, although none have been approved yet.
How common is it?
Nipah was first identified in Malaysia in 1999. Since then, there have been small outbreaks almost every year, mostly in Bangladesh. India is also seeing sporadic outbreaks.
According to the Coalition for Epidemic Preparedness Innovations (CEPI), a group that tracks new disease threats and funds the development of medical tools to protect against them, a total of 750 cases were recorded in December, and 415 of the patients died. Reuters traced the spread of Nipah in a 2023 series, Bat Lands.
Read more: Pakistan tightens border surveillance over Nipah virus
How does it spread?
When Nipah was first identified in Malaysia, it spread largely through direct contact with sick pigs or contaminated tissue. Since then, it is more commonly spread from contact with what scientists say is its natural host: fruit bats. More specifically, the consumption of fruit or fruit products – such as raw date palm juice – containing urine or saliva from infected fruit bats has been the most likely source of infection, the WHO says.
Human-to-human spread has been found, mainly after close contact between a sick patient and their family or caregivers.
What are the symptoms?
The initial symptoms of Nipah such as fever, headache and muscle pain are not specific and can be confused with other diseases. These can then be followed by neurological signs indicating acute encephalitis or inflammation of the brain, and some people experience severe respiratory problems.
Seizures occur in severe cases, progressing to coma in days. Most people who get better make a full recovery, but some experience long-term neurological problems.
How concerned should we be?
While Nipah is a dangerous disease with high mortality, it has yet to show signs of becoming more transmissible among humans or spreading easily across the world, scientists say. However, it remains a significant public health problem, according to the WHO, especially in countries where outbreaks are more common.
It can also lead to the mass killing of farm animals such as pigs that are susceptible to the virus. However, researchers say it is unlikely to spread globally – and also point out that airport screening may be ineffective as the virus has a long incubation period.
What vaccines or treatment are available?
There are currently no approved vaccines or treatments for Nipah, although a number of candidates are undergoing testing, including one developed by Oxford University researchers involved in developing one of the Covid-19 vaccines.
Their Nipah vaccine uses the same technology and began Phase II testing in Bangladesh in December in collaboration with the International Center for Diarrheal Disease Research, Bangladesh and with funding from CEPI.
