Health officials in India have shuttered schools, offices, and public transport and are testing hundreds of people in an effort to track and contain an outbreak of Nipah virus that has killed two people, but can kill as many as three in four people it infects and has been flagged by experts as having the potential to seed a new pandemic.

Nipah is a rare and potentially deadly virus that was first discovered in 1999 after an outbreak among pigs and pig farmers in Malaysia and Singapore.

Nipah is a zoonotic virus—meaning it can spread from animals to humans—and can infect humans through direct contact with infected animals or their bodily fluids or after eating contaminated food such as fruit products contaminated with urine or saliva from infected bats.


Cases of human-to-human transmission of Nipah have also been reported during past outbreaks, particularly among the families and caregivers of infected people.

In humans, symptoms typically arise between a few days and two weeks after infection, according to the World Health Organization, though periods as long as 45 days have been reported and it’s possible people may be infectious during this time (the WHO says pigs are “highly contagious” during this incubation period).

Nipah symptoms typically start with fever, headache and signs of respiratory illness like coughing that can rapidly worsen to brain swelling (encephalitis) and seizures that lead to a coma within a day or two.

Between 40% to 75% of people infected with Nipah will die from the virus, health agencies estimate, with the specific rate depending on the outbreak and strength of local medical systems managing the disease (long term neurological conditions like seizures and personality changes have been reported among those who recover from encephalitis).

Health officials in India’s southern state of Kerala are rushing to track and contain an outbreak of Nipah that has already killed two people and hospitalized three others.

According to news reports, public health workers have tested hundreds of workers, and schools, government buildings, religious institutions, public transport, and public offices have been closed or suspended in at-risk areas to curb potential spread. It is the state’s fourth outbreak since 2018 and experts warn the area might be at particular risk from virus spillovers given the destruction of natural bat habitats by humans in the region.