Japanese encephalitis virus (JEV) is a flavivirus related to dengue, yellow fever and West Nile viruses, and is spread by mosquitoes (especially Culex tritaeniorhynchus).
JEV is the main cause of viral encephalitis in many countries of Asia with an estimated 100 000 clinical cases every year.
Although symptomatic Japanese encephalitis (JE) is rare, the case-fatality rate among those with encephalitis can be as high as 30%. Permanent neurologic, cognitive and behavioural sequelae occur in 30–50% of those with encephalitis.
The majority of cases occur in children below 15 years of age.
Twenty-four countries in the WHO South-East Asia and Western Pacific Regions have endemic JEV transmission, exposing more than 3 billion people to risks of infection.
There is no cure for the disease. Treatment is focused on relieving severe clinical signs and supporting the patient to overcome the infection.
Safe and effective vaccines are available to prevent JE. WHO recommends that JE vaccination be integrated into national immunization schedules in all areas where JE disease is recognized as a public health issue.
Japanese Encephalitis
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