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Communicable Diseases Agency

Japanese encephalitis

Japanese encephalitis is a mosquito-borne disease caused by the Japanese encephalitis virus.

Last updated 31 March 2026

What is Japanese encephalitis?

Japanese encephalitis is a mosquito-borne disease caused by the Japanese encephalitis virus.

How is Japanese encephalitis transmitted?

Japanese encephalitis spreads to humans through bites from the Culex species mosquitoes. It acquires the Japanese encephalitis virus from infected pigs and wild birds.

What are the symptoms of Japanese encephalitis?

Most people infected with Japanese encephalitis do not experience any symptoms. Some may develop relatively mild forms of the disease and less than 1% of those infected develop severe brain inflammation.

In those experiencing the severe form of the disease, common symptoms include:

  • Fever

  • Headache

  • Abdominal pain, nausea and vomiting

  • Confusion and drowsiness

  • Parkinson-like symptoms

  • Paralysis

  • Seizure – commonly in children

  • Coma

What are the risk factors?

Living in or travelling to Japanese encephalitis-affected areas.

How is Japanese encephalitis treated?

There is no specific antiviral treatment for Japanese encephalitis. Treatment is mainly supportive.  Severe cases would require hospitalisation and close monitoring for complications (e.g., increased intracranial pressure, seizures, and airway compromise) and medical management.

How to prevent Japanese encephalitis?

Japanese encephalitis vaccination is available in Singapore. The vaccine is recommended for persons travelling to Japanese encephalitis-affected areas for more than 1 month and are staying or working in rural areas. Please consult your doctor 4 to 6 weeks prior to travelling for a health risk assessment for advice on required or recommended vaccinations.

Travellers who are at risk should take precautions against mosquito bites in addition to vaccination. These precautions include:

  • Staying in rooms which are well-screened from insects from the exterior.

  • Wearing long, protective clothing that covers most of one’s body.

  • Using effective insect repellent (e.g.those containing DEET, Picaridin, or IR3535 as the active ingredient) and re-applying every four to six hours on exposed skin.