Nipah virus is a zoonotic virus that causes disease in both animals and humans. It was first identified during an outbreak in Malaysia and Singapore in 1998-1999. The natural host is fruit bats of the Pteropodidae family, and it is transmitted to other animals and humans through contact with bat secretions or excretions. In humans it causes a range of illnesses from asymptomatic infection to fatal encephalitis. Outbreaks have occurred in Bangladesh, India and other Southeast Asian countries. There is no vaccine available for humans currently, though supportive care is provided for infected individuals.