Nipah virus

Nipah virus (NiV), also called Nipah henipavirus, is a zoonotic pathogen in the genus Henipavirus. It was first recognized during an outbreak among pig farmers in Malaysia in 1998–1999, with related cases in Singapore. The virus was isolated from a patient from Sungai Nipah village in Malaysia, from which its name derives. Fruit bats of the family Pteropodidae, especially flying foxes of the genus Pteropus, are considered its natural hosts. The bats generally do not show disease from infection.

People can become infected through contact with infected animals, including bats and pigs, or by consuming food contaminated by infected bats. WHO identifies raw date palm sap contaminated by bats as one possible route. Person-to-person transmission has also occurred, particularly through close contact with infected people and their body fluids, including in healthcare and caregiving settings. Nipah outbreaks have been reported in Bangladesh, India, Malaysia, the Philippines and Singapore. Bangladesh has reported outbreaks repeatedly, while India has experienced recurrent, geographically limited outbreaks, including events reported by WHO in 2026. Animal reservoirs and spillover risk mean that local public-health authorities monitor suspected cases and contacts.

The incubation period is usually several days to two weeks, although longer periods have been reported. Some infections may be asymptomatic. Illness can begin with fever, headache, muscle pain, vomiting or sore throat and may progress to dizziness, drowsiness, confusion, seizures or encephalitis (inflammation of the brain). Some patients develop respiratory illness, which can be severe. Because the early symptoms are not specific to Nipah, laboratory testing is required for diagnosis; methods include real-time polymerase chain reaction (RT-PCR) on appropriate clinical samples and antibody testing. Suspected infections require careful assessment and infection-control precautions by trained health professionals.

There is currently no licensed vaccine or specific antiviral treatment for Nipah virus disease. Care focuses on early recognition, close monitoring and supportive treatment for complications, such as breathing difficulties, encephalitis, dehydration or damage to other organs. Candidate medical countermeasures are under development. Prevention aims to reduce exposure to infected bats and animals, avoid potentially contaminated food such as raw date palm sap in affected areas, and prevent person-to-person spread through appropriate precautions. WHO recommends hand hygiene and avoiding unprotected close contact with ill people; healthcare settings should apply infection-prevention and control measures appropriate to suspected or confirmed cases.

WHO estimates that the case-fatality rate in reported outbreaks has ranged from 40% to 75%; the rate varies with outbreak circumstances and access to early detection and clinical care. This high severity, the ability to spread from animals to people and between close contacts, and the absence of licensed vaccines or specific medicines make Nipah a priority for public-health preparedness and research. A reported cluster or single case does not by itself mean that widespread transmission is occurring: outbreak risk assessments depend on verified case counts, contact tracing and evidence of secondary spread. In a 2026 report on a confirmed Kerala case, WHO described contact tracing and public-health controls while noting no secondary cases reported as of its specified reporting date.