Last updated:
Related diseases:
The first detection of Japanese encephalitis virus (JEV) this summer has been confirmed in a mosquito in rural Victoria during routine testing.
What is JEV?
JEV is a virus that spreads through bites from infected mosquitoes. The virus can cause a rare but serious infection of the central nervous system.
For most people, JEV infection is mild and only about 1% to 4% of people get any symptoms. However, for those who do, it can be very serious and cause severe complications.
JEV detected in south-eastern Australia
In 2022, JEV was detected in south-eastern Australia for the first time, with 45 human cases and 7 deaths reported between 1 January 2021 and 31 December 2022. Nine cases and 5 deaths were reported in 2024–25, with many more cases likely going unreported because, in most instances, people don’t have any symptoms.
JEV is a significant public health concern because of its severity in some people and because it’s hard for us to know exactly where it’s circulating in Australia. This makes it difficult to anticipate what impact it could have in the future.
For these reasons, it is important people are aware of:
- the symptoms of JEV
- the effective vaccine that is available
- other ways they can reduce their risk of contracting the virus.
People at greater risk of exposure
We do know that you are more likely to be exposed if you:
- work or enjoy leisure activities outdoors – like camping, fishing, hiking or gardening – in areas where JEV is present
- travel to areas where JEV is present, especially in peak transmission season (year-round in northern Australia and mid-spring to late autumn in south-eastern Australia)
- work with or live close to pigs and waterbirds
- work with mosquitoes, such as environmental health officers or entomologists
- live or work on the outer islands of the Torres Strait.
Symptoms
Common early symptoms include:
Neurological symptoms might then develop over the following few days, including:
- confusion and agitation
- paralysis
- convulsions and seizures
- coma.
Read more about symptoms, diagnosis and treatment of Japanese encephalitis.
How can I avoid contracting JEV?
An effective preventive vaccine for JEV is available for people at higher risk of contracting the virus in Australia. See if you’re eligible for free vaccination in your state or territory.
If you are not eligible for a free JEV vaccine but at higher risk, you can talk to your healthcare professional about buying one privately.
Read more about Japanese encephalitis vaccination.