Nipah virus (NiV) is a zoonotic virus that spreads between animals and people. It was first discovered in 1999 following an outbreak of disease in pigs and people in Malaysia and Singapore, which resulted in nearly 300 human cases. NiV is a member of the family Paramyxoviridae, genus Henipavirus, and is genetically related to Hendra virus, another henipavirus known to be carried by bats. The animal host reservoir for NiV is the fruit bat, also known as the flying fox. NiV can also spread through pigs and other animals like goats, horses, dogs, or cats.

Nipah virus infection can be prevented by avoiding exposure to sick pigs and bats in areas where the virus is present, and not drinking raw date palm sap which can be contaminated by an infected bat. During an outbreak, standard infection control practices can help prevent person-to-person spread in hospital settings. Symptoms of NiV infection can range from a mild fever and headache to brain infection or death, with a case fatality rate estimated at 40% to 75%. There are currently no drugs or vaccines specific for Nipah virus infection, although several are currently in clinical trials.