About Japanese encephalitis
Japanese encephalitis is caused by the Japanese encephalitis virus (JEV). It is spread through bites from mosquitos, which become infected through biting infected pigs and waterbirds.
JEV is endemic to parts of Asia and the Torres Strait region of Australia. JEV has now also been detected in humans, animals and mosquitos in mainland Australia.
Infection in humans is most commonly asymptomatic, but on rare occasions it can result in severe disease and even death.
Animals can be infected with JEV but they cannot transmit the virus to humans. It cannot be transmitted from human to human, or by eating meat from an infected animal. For information about JEV and animals visit the Department of Agriculture, Water and the Environment website.
Japanese encephalitis virus as a Communicable Disease Incident of National Significance
On 4 March 2022, Australia’s Acting Chief Medical Officer declared the Japanese encephalitis virus outbreak a Communicable Disease Incident of National Significance, following the detection of human cases of JEV across multiple states on mainland Australia.
The Department of Health and Aged Care in partnership with the Department of Agriculture, Fisheries and Forestry coordinated a national One Health response to the outbreak The response included:
- Working with key stakeholders, including states and territories, to coordinate the national response, develop a Joint National JEV Outbreak Response Plan, share information, and support risk understanding and mitigation activities;
- Enhancing JEV surveillance, through the development and delivery of mosquito surveillance and control activities, sero-surveillance and geospatial mapping projects;
- Delivering a national Communications Strategy, including a dedicated national communications campaign, development of targeted resources, and sharing public health information and prevention messaging; and
- Securing immediate and ongoing access to vaccines to support the initial outbreak response.
On 16 June 2023, the Chief Medical Officer stood down Australia’s CDINS declaration for Japanese encephalitis virus (statement) in recognition that the reduction in risk and national preparedness to manage any future outbreaks has reduced the need for a nationally coordinated and dedicated response.
States and territories will continue to manage the risk of JEV in line with local arrangements, and people should remain vigilant to avoid mosquito bites, and aware of JEV symptoms.
How to protect yourself
There are 2 ways to protect yourself from JEV infection:
- Avoid being bitten by mosquitos
- Receive a vaccination for the virus.
You can protect yourself from being bitten by mosquitos by:
- applying and regularly reapplying an effective insect repellent on exposed skin- the best repellents contain diethyltoluamide (DEET), picaridin, or oil of lemon eucalyptus (always follow label directions)
- 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.
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
If you believe you may be infected with the JEV, seek urgent medical assistance.
Japanese encephalitis is confirmed through a combination laboratory testing and clinical assessment.
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.
Free vaccination is available for priority groups through the states and territories (see JEV local information below for further details).
Find out more about the JEV vaccine.
JEV vaccine for travellers to Asia and the Torres Strait
Vaccination against JEV is recommended if you are travelling to Asia and the Torres Strait region of Australia and plan to:
- travel in rural areas and undertake outdoor activities associated with an increased risk of mosquito bites (such as camping and hiking), or will be staying in accommodation without air-conditioning, screens or bed nets
- spend a month or more in the region.
You should avoid mosquito bites when you are in these areas.
Talk to your GP about how to access a vaccine if you are not eligible for free vaccination.
JEV local information
You can find more information about JEV in your local area, including vaccination eligibility, via your state or territory page:
- New South Wales
- South Australia
- Australian Capital Territory
- Western Australia
- Northern Territory