Japanese encephalitis virus (JEV)

yellow fever and West Nile viruses, and is spread by mosquitoes.
JEV is the main cause of viral encephalitis in many countries of Asia with an estimated 68 000 clinical cases every year.
The case-fatality rate among those with encephalitis can be as high as 30%. Permanent neurologic or psychiatric sequelae can occur in 30%–50% of those with encephalitis.
24 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.

without apparent symptoms. The case-fatality rate can be as high as 30% among those with disease symptoms.
Of those who survive, 20%–30% suffer permanent intellectual, behavioural or neurological problems such as paralysis, recurrent seizures or the inability to speak.

mosquitoes of the Culex species (mainly Culex tritaeniorhynchus).
There is no antiviral treatment for patients with JE. Treatment is supportive to relieve symptoms and stabilize the patient.
Safe and effective JE vaccines are available to prevent disease.
All travellers to Japanese encephalitis-endemic areas should take precautions to avoid mosquito bites to reduce the risk for JE. Personal preventive measures include the use of repellents, long-sleeved clothes, coils and vaporizers. Travellers spending extensive time in JE endemic areas are recommended to get vaccinated.