Japanese encephalitis virus (JEV)

Japanese encephalitis virus (JEV) is a rare but potentially serious infection in humans that is transmitted by a bite from an infected mosquito.

Infection in humans is most commonly asymptomatic, however in less than 1% of infections, it can result in severe disease called encephalitis that requires hospitalisation and can result in serious long-term outcomes.

What you need to know in the ACT

In early 2022, JEV was detected for the first time in commercial pig farms and in humans in New South Wales, northern Victoria, South Australia and Queensland - indicating the virus is likely circulating in the mosquito population where it hasn’t been found before.

There have been no confirmed human cases of JE in the ACT at this time, however residents of Canberra and surrounding areas should take action to avoid mosquito bites.

We are monitoring the situation closely and will provide updates on the latest health advice via our Public Health Alerts page and our social media channels:


Less than 1% of people infected with JEV will experience symptoms. If symptoms do develop, it is usually 5 to 15 days after a bite from an infected mosquito

Some infected people experience an illness with fever and headache.

People with severe infection (encephalitis) may experience neck stiffness, confusion, disorientation, tremors, coma or seizures.

If you experience these symptoms, you should seek urgent medical assistance.

How JEV spreads

Infection in humans occurs following a bite from an infected mosquito. Mosquitoes can become infected after biting an infected pig or waterbird. Mosquitoes cannot become infected after biting infected humans.

JEV cannot be passed from person to person.

Humans cannot become infected by eating meat from an infected animal.


Actions to protect yourself against mosquito bites include:

  • Covering up as much as possible with loose-fitting light-coloured clothing and covered footwear when outside.
  • Using an effective insect repellent on exposed skin and reapply within a few hours. The best mosquito repellents contain Diethyl Toluamide (DEET), Picaridin, or oil of lemon eucalyptus.
  • Using insecticide sprays, vapour dispensing units (indoors) and mosquito coils (outdoors) to clear rooms or repel mosquitoes from an area.
  • Covering all windows, doors, vents and other entrances with insect screens.
  • Removing any water-holding containers outside the house where mosquitoes could breed.
  • Ensuring accommodation, including tents, are properly fitted with mosquito nettings or screens.

More information can be found on our Mosquitoes - risk and prevention page.


Safe and effective vaccines for Japanese encephalitis virus (JEV) are available in Australia for people aged two months and over. These vaccines are not on the National Immunisation Program schedule – the list of vaccines that are provided free of charge for children and adults in Australia. JEV vaccines are being prioritised for those currently at highest risk of JEV.

    The groups currently eligible to receive a government funded JEV vaccine in the ACT are:

    • People involved with piggeries/pork industry as per one of the following categories:
      • works or resides at, or has planned, a non-deferable visit to a piggery, including but not limited to farm workers and their families (including children aged 2 months and older) living at the piggery.
      • transport workers who transport pigs to piggeries, veterinarians and others involved in the care of pigs at piggeries.
      • works at, or has a planned, a no-deferable visit to a pork abattoir or pork rendering plant.
    • People working directly with mosquitoes through their surveillance (field or laboratory based) or control and management, and indirectly through management of vertebrate mosquito-borne disease surveillance systems (e.g., sentinel animals) such as:
      • environmental health officers and workers (urban and remote).
      • entomologists or other personnel who work directly with mosquitoes.
    • All diagnostic and research laboratory workers who may be exposed to the virus. Such as persons working with JEV cultures or mosquitoes with the potential to transmit JEV, as per the Australian Immunisation Handbook.
    • People who are engaged or have the potential to undertake prolonged outdoor work in areas of high JEV concern. Examples include recovery efforts (clean up) of stagnant waters following floods. Areas of high JEV concern include local government areas in NSW, Victoria, South Australia, and Queensland.

    ACT Health has sent a letter to eligible people (through their workplaces) advising how to book in for a JEV vaccination. If you believe you are eligible for a JEV vaccination and have not received a letter through your workplace, you can either contact the ACT Health Immunisation Unit for further information on 02 5124 9800 or discuss with your general practitioner (GP).

    A letter was sent to ACT GPs in December 2022 outlining the eligibility criteria and process for ordering a JEV vaccine and is available here.

    The JEV vaccine order form for GPs is available here.


    JEV infection is usually diagnosed by measuring levels of antibodies to JEV in samples of blood or spinal fluid. If you have been infected, you do not put others at risk, as this disease cannot be passed from person to person. 

    If you have symptoms consistent with JEV please seek medical treatment.


    There is no specific treatment available for JEV. The best way to avoid infection is to avoid being bitten by mosquitoes.

    Information for Health professionals

    JEV in humans is a notifiable disease in the ACT and requires immediate telephone notification on diagnosis or based on reasonable clinical suspicion.

    Clinicians should consider a diagnosis of JEV infection in patients presenting with unexplained symptoms and signs consistent with encephalitis – they should be referred to hospital for further investigation and management.

    More information for clinicians can be found on the Chief Health Officer alerts for health professionals page.

    For more information about notifiable diseases and how to notify, refer to the Disease Surveillance webpage.

    Information about Mosquitoes - risk and prevention

    Visit this webpage.

    JEV in animals

    JEV in animals is a nationally notifiable disease. For more information about protecting animals in your care, and what to do you if you suspect an animal is showing signs of the disease, please refer to the Environment, Planning and Sustainable Development Directorate website for more information.

    Page last updated on: 6 Dec 2023