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Japanese encephalitis

did you know?

Japanese encephalitis is transmitted to humans from pigs and wading birds through the bite of an infected mosquito.

Japanese encephalitis - What is it?

Japanese encephalitis is a viral disease caused by the Japanese encephalitis virus (JEV) that is transmitted through the bite of an infected mosquito.

Japanese encephalitis - Who is at risk?

JEV is found in many parts of Asia - including China, the Indian subcontinent and South East Asia - and occasionally in the Torres Strait and far north Queensland.

The disease most often occurs in rural agricultural areas, especially those with rice production and flooding irrigation.

The risk of contracting Japanese encephalitis during travel varies depending on a number of factors, such as:

  • the season of travel (mainly the wet season)
  • the regions visited (particularly in rural agricultural areas associated with rice production and flooding irrigation systems)
  • the length of stay
  • the extent of outdoor activities
  • the type of measures taken to avoid mosquito bites
  • whether you have been vaccinated against Japanese encephalitis

Other people may be at risk of JEV infection. Please speak to your doctor regarding your individual circumstances.

Japanese encephalitis - How is it spread?

Pigs and wading birds carry the virus. The virus is then passed to humans by mosquitoes.

Japanese encephalitis - What are the symptoms?

Most people infected with JEV do not develop any symptoms. For those who do, symptoms usually appear within 5-15 days after infection.

Early, mild symptoms can include fever, headache and vomiting. People may then experience convulsions, disorientation, general weakness and movement disorders.

A severe complication of Japanese encephalitis is encephalitis (brain inflammation), up to 30% of people who develop this complication may die.

Up to half the people that survive the illness will continue to experience problems with different brain functions.

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

Japanese encephalitis – Vaccination and Prevention

Travellers to regions where the Japanese encephalitis virus exists are recommended to avoid mosquito bites by:

  • using mosquito repellents, coils and sprays
  • using mosquito nets
  • wearing appropriate clothing
  • reduce exposure to mosquitoes during times when they bite the most (dusk to dawn)

Australian health authorities recommend vaccination with a Japanese encephalitis vaccine for travellers in situations where their risk of infection may be increased. Examples of this include travellers who stay more than 1 month in high risk countries, short term travellers that visit during the wet season, travellers that partake in significant outdoor activities or stay in accommodation that has not been mosquito proofed.

In addition the vaccine is recommended for all travellers staying for a year or more in Asia (except Singapore) and  for all residents of the outer islands in the Torres Strait (far north Queensland) and those travelling to the area during the wet season (December to May).

Japanese encephalitis – Treatment

There is no specific treatment for Japanese encephalitis. Infected people may require hospitalisation where they will receive care to relieve symptoms and 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 your doctor at least 6 to 8 weeks before you travel to discuss vaccination and travel health.


Some side effects may be experienced following vaccination. Please discuss any side effects or concerns with a healthcare professional.




AUS/VAC/0025/15. Date of approval: March 2015.