Hendra virus disease (HeV infection) is caused by a virus in the Paramyxoviridae family, genus Henipavirus. HeV was initially discovered in 1994 from specimens taken in Hendra, a suburb of Brisbane, Australia, during an outbreak of respiratory and neurologic illness in horses and people. The Nipah virus, also a species belonging to the genus Henipavirus, is linked to this one.
Since then, researchers have determined that the flying fox acts as the natural reservoir for the Hendra virus (bats of the genus Pteropus). Infections caused by the Hendra virus in humans have remained extremely uncommon since 1994; as of 2013, just seven instances had been documented.