Japanese encephalitis

Japanese encephalitis (JE) is a rare but potentially serious illness caused by the Japanese encephalitis virus. The JE virus 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.

Find out more about JE vaccination.

What you need to know

In early 2022, the JE virus 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.

For large parts of mainland Australia, the risk of JE is here to stay.

The JE virus has not been found in mosquitoes in the ACT at this time. There have been no confirmed cases of JE transmitted to humans in the ACT. However, residents of Canberra and surrounding areas should continue to take steps to avoid mosquito bites.

We monitor the situation closely and will provide updates on the latest health advice on the public health alerts page and our social media channels:

Symptoms

Less than 1% of people infected with the JE virus 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 Japanese encephalitis is spread

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.

JE cannot be passed from person to person.

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

Prevention

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.

Find out more information on protecting yourself against mosquitoes.

Diagnosis

JE 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 JE, please seek medical treatment.

Treatment

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