The risk of infection is greatest in parts of Southern and Eastern Asia, the Indian subcontinent, and Southeastern Russian Federation. In all areas, the risk of infection is greatest in rural areas and changes with the season. An estimated 30,000 to 50,000 cases and 10,000 deaths occur each year, mostly among children. In endemic areas, the annual incidence of clinical disease ranges from 10-100 per 100,000 population. Children less than 15 years of age are principally affected.
Most infections result in mild symptoms or no symptoms at all.
About 30 percent of survivors will have serious neurological and psychiatric sequelae. There is no specific treatment for Japanese encephalitis. Care of patients focuses on treatment of symptoms and complications. Vaccination is the single most important measure to control Japanese encephalitis. The only vaccine that is commercially available on the international market is the mouse brain-derived inactivated vaccine.