Nipah virus has caused recurrent outbreaks in Bangladesh and Western India and the most recent outbreak in Kerala in 2018 was the first recorded in Southern India. Some of these outbreaks involved human-to-human transmission, showing the risk of this virus becoming more widespread. It is however a zoonotic disease so it can spread between animals and people. Fruit bats of the Pteropus genus, or flying foxes, are the main reservoir for NiV. Agricultural practices are also key factors in the disease spreading to humans. For example, in Malaysia, the first reported Nipah outbreak led to 265 human cases and 105 deaths, intensification of pig farming and cultivation of fruit trees in the same locations was an important determinant of the outbreak. The outbreak was ultimately stopped by the slaughtering of over 1 million pigs.
In Bangladesh and India, consumption of raw palm sap is the main route of transmission of the virus to humans.