Japanese encephalitis, caused by Japanese encephalitis virus, represents the most significant etiology of arboviral encephalitis worldwide. About 35,000–50,000 cases and 10,000–15,000 deaths are reported annually. Japanese encephalitis virus is spread throughout mostly rural areas of Asia, mainly by culicine mosquitoes, where children are most often affected by the disease with an incidence of 5–50 cases per 100,000 children per year. The disease is relatively uncommon among travellers to endemic areas. Most people who are infected develop mild symptoms or no symptoms at all;in people who develop a severe disease,the initial symptoms include fever, headache, nausea and vomiting and the disease can then progress to encephalitis. Laboratory tests are essential for diagnosis. There is no specific treatment available, but vaccination is efficient in disease prevention.