The clinical epidemiology of neurological disease caused by flaviviruses varies. JEV is numerically the most important cause of encephalitis with up to 70,000 cases annually across Asia.Almost all those living in rural Asia become infected during childhood, but only a small proportion develops neurological disease. Clinical features include a non-specific febrile illness, aseptic meningitis, febrile seizures, encephalitis, with Parkinsonian movement disorders, and myelitis, causing a poliomyelitis-like flaccid paralysis.There is no specific treatment, but good supportive care is essential. There is no specific treatment, but good supportive care is essential.