Symptoms & Treatment


Less than 1% of people infected with Japanese encephalitis (JE) virus develop neurologic illness. In persons who develop symptoms, the time from infection until illness onset (incubation period) is typically 5-15 days.

  • Initial symptoms often include fever, headache, and vomiting.
  • Mental status changes, neurologic symptoms, weakness, and movement disorders might develop over the next few days.
  • Seizures are common, especially among children.
  • Among patients who develop encephalitis (infection of the brain), 20% – 30% die.
  • Although some symptoms improve after the acute illness, 30%-50% of survivors continue to have neurologic, cognitive, or psychiatric symptoms.


See your healthcare provider if you have traveled to an area where JE is present and develop the symptoms described above.

  • Tell your healthcare provider when and where you traveled.
  • Your healthcare provider can order tests to look for JE virus infection.

To learn more about testing, visit our Healthcare Providers page.


  • No specific treatments have been found to benefit patients with JE. Treatment is symptomatic. However, a vaccine is available to prevent disease.
  • Rest, fluids, and over-the-counter pain medications may relieve some symptoms.
  • Hospitalization for supportive care and close observation is generally required.

To learn more about treatment, visit our Healthcare Providers page.