A young travelling woman smiling and walking with her luggage on her back.

This virus is passed from animals to humans through the bite of infected mosquitoes. It can lead to serious, long-term brain complications.

Did you know?

  • The Japanese encephalitis virus is found mainly in pigs and wading birds and is passed to humans through the bite of an infected mosquito.
  • It is common in many parts of Asia including China, the Indian subcontinent and Southeast Asia.
A traveler walking through a busy Asian street wearing a fedora.

What is it?

Japanese encephalitis is a viral disease caused by the Japanese encephalitis virus. It’s a mosquito-borne virus that causes mild symptoms in most cases but can lead to inflammation of the brain (encephalitis) in a small percentage of cases. 

What are the symptoms?

Most people infected with Japanese encephalitis do not develop any symptoms. For those who do, symptoms usually appear within five to fifteen days of infection. 

The early symptoms of Japanese encephalitis are mild and can include fever, headache, vomiting difficulty moving and confusion. Symptoms can progress to swelling of the brain (encephalitis).

Up to half the people that survive the illness will develop brain damage.1

This is not a full list of symptoms that can occur following Japanese encephalitis infection. If you feel unwell while travelling or when you return home, make sure you see a healthcare professional as soon as possible.

How is it spread?

Pigs and wading birds carry the virus, which is passed to humans by mosquitoes.

Who is at risk?

Travellers going to areas where Japanese encephalitis is common are most at risk. Japanese encephalitis is found in many parts of Asia, including China, the Indian subcontinent and South East Asia. It has also appeared in the Torres Strait. The disease most often occurs in rural agricultural areas, especially those with rice production and flooding irrigation.

The risk is very low for most travellers but can vary depending on:

  • the season of travel (higher risk in the wet season)
  • the regions visited (higher risk in rural agricultural areas associated with rice production and flooding irrigation systems)
  • the length of stay
  • whether you are outdoors a lot
  • the measures taken to avoid mosquito bites
  • whether you have been immunised.

Other people may be at risk of Japanese encephalitis infection. Please speak to a healthcare professional regarding your individual circumstances.

Prevention and Treatment Options

  • Travellers

    If you’re travelling to a region where Japanese encephalitis exists, you should take measures to avoid mosquito bites.

    • Use mosquito repellents, coils and sprays
    • Use mosquito nets
    • Wear appropriate clothing (long-sleeved shirts, long pants and hats).
    • Reduce exposure to mosquitoes during times when they bite the most (dusk to dawn).

    The risk of Japanese encephalitis can be reduced through immunisation.

    The risk of infection will depend on your travel plans and planned activities, such as;

    • staying more than 1 month in high risk countries
    • visiting during the wet season
    • taking part in lots of outdoor activities
    • staying in accommodation that has not been mosquito-proofed (no air conditioning, screens or bed nets).

    There is no specific treatment for Japanese encephalitis if infected, you may require hospitalisation where you will be closely observed. Encephalitis treatment may involve pain and fever medications in addition to rest and fluids to relieve the symptoms.

    It is important to plan ahead and see a healthcare professional at least 6 to 8 weeks before you travel to discuss prevention options and travel health.


  1. Australian Technical Advisory Group on Immunisation (ATAGI). Australian Immunisation Handbook, Australian Government Department of Health, Canberra, 2018, immunisationhandbook.health.gov.au.(accessed October 2020)

PM-AU-AVX-WCNT-190038 Date of GSK Approval: January 2021