Japanese encephalitis virus (JEV) is a mosquito-borne virus that can cause inflammation of the brain, known as encephalitis. It is primarily found in rural areas of Asia and the Western Pacific, where the virus is transmitted to humans through bites from infected Culex mosquitoes. Most people infected with JEV do not show symptoms, but about 1 in 250 cases can lead to severe neurological complications or death. Vaccination is available and recommended for travelers to high-risk areas, as there is no specific antiviral treatment for the disease.