Nipah virus infection

Nipah virus (NiV) is a zoonotic virus, usually transmitted from animals to humans, but can also be transmitted through contaminated food or directly between people. Transmission of the virus to humans can occur from direct contact with infected animals like bats, pigs or horses, and by consuming fruits or fruit products, such as raw date palm juice, contaminated by infected fruit bats. 

In infected people, it causes a range of illnesses from asymptomatic (subclinical) infection to acute respiratory illness and fatal encephalitis. The incubation period – that is the time from infection to the onset of symptoms – ranges from 3 to 14 days. In some rare cases incubation of up to 45 days has been reported.

There are currently no drugs or vaccines that specifically target Nipah virus infection. WHO has identified Nipah as a priority disease for the WHO Research and Development Blueprint.

India has recently reported two laboratory confirmed case of Nipah virus disease, from North 24 Parganas district, West Bengal in the last week of December 2025. Coordinated efforts for public health response by the Central and State health authorities for enhanced surveillance, laboratory testing, field investigations and risk communications have enabled timely containment of the outbreak.

WHO assesses the overall risk of the current spread of the outbreak as moderate at Sub-national level and low at National, Regional and Global level. WHO does not recommend any travel and/or trade restrictions for India based on current information. 

For some people, Nipah virus infection may be asymptomatic. However, most people develop a fever, and symptoms involving the brain (such as headache or confusion), and/or the lungs (such as difficulty breathing or cough). Other organs can also be affected. Frequent other symptoms include chills, fatigue, drowsiness, dizziness, vomiting and diarrhoea. 

Severe disease can occur in any patient but is particularly associated with people presenting with neurological symptoms, with progression to brain swelling (encephalitis) and, frequently, death. Careful supportive care and monitoring during this period is critical. 

Most people who survive make a full recovery, but long-term neurologic conditions have been reported in approximately 1 in 5 people who recovered from the disease. The case fatality rate of Nipah virus infection is estimated at 40–75% but can vary by outbreak depending on surveillance and clinical management in affected areas.

There are currently no approved drugs or vaccines for Nipah virus infection. WHO has identified Nipah as a priority disease for the WHO Research and Development Blueprint. A range of candidate products are under different stages of development. 

Early intensive supportive care is recommended to treat severe respiratory and neurologic complications and can improve survival.