About Japanese encephalitis

Japanese encephalitis is caused by the Japanese encephalitis virus (JEV). It is spread through mosquito bites and is more common in areas of increased mosquito activity. It is endemic to parts of Asia and the Torres Strait region of Australia.

Animals can be infected with the Japanese encephalitis virus, but they cannot transmit the virus to humans. It cannot be transmitted from human to human, or by eating meat from an infected animal.

Infection in humans is most commonly asymptomatic, but on rare occasions it can result in severe disease and even death.  

Disease type: 
Vectorborne
Vaccination available under NIP: 
No
Notifiable disease: 
Yes

How to protect yourself

There are 2 ways to prevent Japanese encephalitis:

  1. Receive a vaccination for the virus.
  2. Avoid being bitten by mosquitos.

You can protect yourself from being bitten by mosquitos by:

  • applying and regularly reapplying an effective insect repellent on exposed skin
  • wearing long, loose fitting clothing when outside
  • ensuring accommodation, including tents, are properly fitted with mosquito nettings or screens
  • using insecticide sprays, vapour dispensing units (indoors) and mosquito coils (outdoors) to clear rooms and repel mosquitoes from an area
  • covering all windows, doors, vents and other entrances with insect screens
  • removing any water-holding containers where mosquitoes may breed.

The best mosquito repellents contain diethyltoluamide (DEET), picaridin, or oil of lemon eucalyptus.

Symptoms

Most cases of Japanese encephalitis in people are asymptomatic, however those with severe infection may experience: neck stiffness, coma, and more rarely, permanent neurological complications or death.

Encephalitis is the most serious clinical consequence of a JEV infection.

Illness usually begins with symptoms such as:

  • sudden onset of fever
  • headache
  • vomiting.

If you believe you may be infected with the Japanese encephalitis virus, seek urgent medical assistance.

Vaccination

Vaccination is available for priority groups.

Find out if you need to get a Japanese encephalitis virus (JEV) vaccine.

JEV vaccine for travellers to Asia and the Torres Strait

We recommend vaccination against this disease if you are travelling to Asia and the Torres Strait region of Australia and will be:

  • travelling in rural areas
  • undertaking certain activities with increased risk of exposure
  • spending a month or more in the region.

You should avoid mosquito bites when you are in these areas.

People who work with animals in Australia may also choose to be vaccinated against this disease.

Diagnosis

Japanese encephalitis is confirmed through a combination laboratory testing and clinical assessment.

If you think you may be infected with the Japanese encephalitis virus seek urgent medical assistance.

Treatment

There are no treatments for Japanese encephalitis. You can relieve the symptoms by:

  • getting plenty of rest
  • drinking plenty of fluids
  • taking paracetamol for pain or fever.

In more severe cases, hospitalisation for supportive care and close observation may be required.

Resources

Japanese encephalitis (JEV) resources

These resources cover what JEV is, symptoms, safety measures and how we are responding to the virus.

Japanese encephalitis (JEV) resources for Aboriginal and Torres Strait Islander people

These resources, produced for Aboriginal and Torres Strait Islander people, explain what JEV is, symptoms and safety measures to avoid being bitten by infected mosquitos.

Last updated: 
2 August 2022