Japanese encephalitis (JE) is caused by the Japanese encephalitis virus (JEV), transmitted through mosquito bites, and is the leading type of epidemic encephalitis in Asia. It is prevalent in much of South and Southeast Asia, with case numbers varying significantly across different regions. Although many JEV infections are asymptomatic, those that manifest symptoms can be severe and life-threatening. The natural reservoirs for JEV are ardeid wading birds, while pigs serve as crucial amplifying hosts during human outbreaks. Although safe and effective vaccines for JE exist, their usage remains limited in many endemic areas where they are needed most. Enhanced surveillance and diagnosis of JE are essential, especially as climate change and social disruption are likely to expand the geographical range of Culex mosquitoes and increase JE risk areas.