Key points
- Japanese encephalitis virus spreads through the bites of infected mosquitoes.
- Most people with Japanese encephalitis do not have symptoms or have only mild symptoms.
- Some people develop inflammation of the brain, with symptoms including headache, fever, disorientation, seizures, weakness, and coma.
- Vaccination is recommended for some travelers.
Overview
Japanese encephalitis is a disease caused by a virus spread by infected mosquitoes. Japanese encephalitis virus is the leading cause of vaccine-preventable encephalitis in Asia and parts of the western Pacific. For most travelers to Asia, the risk for Japanese encephalitis is very low but varies based on destination, length of travel, season, and activities.
Symptoms
Most people infected with Japanese encephalitis do not have symptoms or have only mild symptoms. However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including headache, fever, disorientation, seizures, weakness, and coma. Among patients who develop encephalitis, about 1 in 4 (20–30%) die.
How it spreads
Japanese encephalitis virus spreads to people through the bites of infected mosquitoes. Rarely, the virus can also spread through blood transfusion. It can probably also spread through organ transplantation.
Prevention
The best way to prevent Japanese encephalitis is to protect yourself from mosquito bites. Vaccination is recommended for some travelers.
Testing and diagnosis
See your healthcare provider if you have symptoms after being exposed to mosquitoes in an area where Japanese encephalitis virus spreads.
Treatment
No medicines are available to treat Japanese encephalitis. Treatment is focused on relieving symptoms. Rest, fluids, and over-the-counter pain medications may relieve some symptoms. Hospitalization for supportive care and close observation is generally required.
For healthcare providers: Treatment and Prevention of Japanese Encephalitis