This document provides information on Japanese encephalitis (JE), including its classification, epidemiology, transmission, clinical features, diagnosis, treatment and prevention. JE is an arboviral infection transmitted by mosquitoes that primarily affects pigs, horses and humans. It is endemic in parts of Asia and the Pacific. The virus is maintained in a bird-mosquito cycle, with pigs acting as amplifying hosts. Transmission occurs mainly by Culex tritaeniorhynchus mosquitoes. Most human cases are asymptomatic, but it can cause acute encephalitis with high mortality and neurologic sequelae. Prevention focuses on personal protection from mosquito bites and vaccination in at-risk areas.