Japanese encephalitis (JE) is the most important cause of viral encephalitis in Asia. It is a mosquito-borne flavivirus, meaning it is related to dengue, yellow fever and West Nile viruses. The first case of JE was documented in 1871 in Japan.JE is transmitted to humans through bites from infected mosquitoes of the Culex species (mainly Culex tritaeniorhynchus).
Humans, once infected, do not develop sufficient viraemia to infect feeding mosquitoes. There is no antiviral treatment for patients with JE. Few cases have been found in Asia.