Nipah virus explained: risks, symptoms, and why experts aren’t panicking yet

Health authorities in parts of Asia have tightened airport screening after two Nipah virus cases were reported in India, renewing attention on an infection known for severe outcomes in some outbreaks.

Nipah is a rare viral disease that typically jumps from animals to humans, with fruit bats widely cited as a major reservoir. While some infections may show no symptoms, the illness can be extremely serious. The World Health Organization has warned that case fatality rates have ranged from about 40% to 75%, varying with local capacity for detection and care.

Human-to-human spread is possible, but experts say it does not transmit easily, and outbreaks have generally remained limited in size. Nipah was first identified in Malaysia in 1999. Since then, small outbreaks have occurred repeatedly, most often in Bangladesh, with India also experiencing sporadic cases.

Early symptoms can resemble many common illnesses, including fever, headache, and muscle pain. In more severe progression, patients may develop neurological complications consistent with encephalitis, along with possible respiratory distress. In critical cases, seizures can occur and deterioration can be rapid, though many who recover do so fully, while others may face longer-term neurological effects.

Scientists note that although Nipah is dangerous, it has not shown signs of evolving into a virus that spreads efficiently between people or travels widely around the world. They also caution that airport screening alone may have limited impact because the virus can have a long incubation period.

There are currently no approved vaccines or specific treatments, though multiple candidates are being tested. One vaccine effort drawing attention uses technology similar to a COVID-19 vaccine platform and recently entered phase II testing in Bangladesh through international collaboration and funding support.