

Frequently Asked Questions

What is Japanese encephalitis?


Where does Japanese encephalitis occur?


How soon do people get sick after being bitten by an infected mosquito?


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What are the symptoms of Japanese encephalitis?

Most people who are infected develop mild symptoms or no symptoms at all. In people who develop severe disease, initial symptoms include fever, chills, headache, fatigue, nausea and vomiting. The disease can progress to inflammation of the brain (encephalitis) and is often accompanied by seizures. Coma and paralysis occur in some cases.

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How is Japanese encephalitis diagnosed?


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What is the treatment for Japanese encephalitis?

There is no specific treatment. Severe illnesses are treated by supportive therapy which may include hospitalization, respiratory support, and intravenous fluids.

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What should I do if I think a family member might have Japanese encephalitis?

Consult a healthcare provider for evaluation and diagnosis.

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How can people reduce the chance of getting infected?

  • Use insect repellent and wear long pants and sleeves
  • Sleep in air-conditioned or well-screened rooms or use bed nets
  • A vaccine against JE virus is available. Talk to your healthcare provider about whether this vaccine is right for you.

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Who should get Japanese encephalitis vaccine?

JE vaccine is recommended for travelers who plan to spend at least 1 month in endemic areas during the JE virus transmission season. Vaccine should also be considered for the following:

  • Short-term (less than 1 month) travelers to endemic areas during the transmission season, if they plan to travel outside an urban area and their activities will increase the risk of exposure. Higher-risk activities include participating in extensive outdoor activities (such as camping, hiking, trekking, biking, fishing, hunting, or farming) and staying in accommodations without air conditioning, screens, or bed nets.
  • Travelers to an area with an ongoing outbreak.
  • Travelers to endemic areas who are uncertain of specific travel destinations, activities, or duration.

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How long does the Japanese encephalitis vaccination last?

The duration of protection is unknown. For persons aged 17 years and older, a booster dose may be given if the primary two-dose vaccination series was given one year or more previously and there is continued risk of exposure. Although studies are being conducted on the need for a booster dose for children, data are not yet available.

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What are the side effects of Japanese encephalitis vaccination?

Pain and tenderness are the most commonly reported symptoms. Headache, muscle pain and fatigue can also occur.

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I think I got sick from the vaccine, what should I do?

Consult with your healthcare provider. Ask your healthcare provider to report your case to the Vaccine Adverse Events Reporting System (VAERS) if he or she thinks the vaccine has made you sick.

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