Japanese encephalitis

Japanese encephalitis is an infection that can affect the central nervous system and cause serious complications and even death.

It is endemic (regularly found) in parts of Asia and the Torres Strait.

Japanese encephalitis outbreaks in Australia

Before 2021, Japanese encephalitis had rarely been acquired in mainland Australia with cases only in Northern Australia, Cape York and Torres Strait. No locally acquired cases had been detected since 1998.

Since 2022, cases of Japanese encephalitis have been reported in South Eastern states of mainland Australia, including Victoria and NSW

Japanese encephalitis is an urgent notifiable condition, and health authorities are monitoring it. The public health response is to continue:

• vaccinating people at high risk
• raising public awareness of Japanese encephalitis

Most people infected with the Japanese encephalitis virus don't experience any symptoms.

If you do get symptoms, you are likely to notice them about 5 to 15 days after being bitten by an infected mosquito.

The Japanese encephalitis virus can cause encephalitis and meningitis. These conditions are serious, and can cause symptoms such as:

• fever
• vomiting
• headache and neck stiffness
• convulsions and seizures (fits)
• muscle weakness and paralysis
• fatigue
• coma and brain damage

Japanese encephalitis can also make you feel confused or agitated.

Japanese encephalitis is caused by the Japanese encephalitis virus (JEV).

Japanese encephalitis only spreads to humans via bites from infected mosquitoes.

Animals such as pigs, waterbirds and horses can also catch Japanese encephalitis. These animals can't transfer the virus to humans. If you work closely with these animals — especially pigs — you're at increased risk of being bitten by an infected mosquito.

You cannot catch Japanese encephalitis:

• through contact with infected people
• by eating meat from an infected animal

If you have recently been in an area with reports of Japanese encephalitis virus, and you experience sudden symptoms, seek urgent medical attention.

If you think you may have Japanese encephalitis, visit your nearest emergency department or call an ambulance on triple zero (000).

Your doctor can diagnose Japanese encephalitis by asking you about your symptoms. They may also ask if you have recently travelled to any areas where there are cases of JEV.

If your doctor thinks you have Japanese encephalitis, further tests can confirm your diagnosis. These may include a:

• blood test
• lumbar puncture (spinal tap)

Japanese encephalitis is a nationally notifiable disease in Australia. This means, if you are diagnosed with Japanese encephalitis, your doctor will let your local public health authority know. They will check who you have been in contact with and take steps to control an outbreak.

There is no specific medicine or treatment for Japanese encephalitis.

If you have symptoms of Japanese encephalitis, you will likely need treatment in hospital to manage:

• seizures
• encephalitis
• meningitis

Antibiotics will not help you recover because this illness is caused by a virus, not bacteria.

The 2 best ways to prevent Japanese encephalitis are to:

1. avoid being bitten by mosquitoes, especially in areas where the virus is common
2. get vaccinated against Japanese encephalitis virus

What are the recommendations for the Japanese encephalitis virus vaccine?

Vaccination is a safe and effective way to reduce your chance of catching Japanese encephalitis.

Vaccination is recommended for people who:

• live, work or spend time outdoors in areas where Japanese encephalitis virus has been found
• travel to high‑risk areas, especially for activities like camping, caravaning, boating, fishing or hunting
• spend a month or more in Asia or the Torres Strait region of Australia during the wet season
• work in laboratories with Japanese encephalitis virus
• work with mosquitoes
• work with pigs or near piggeries (including farm workers and their families)

See below for details about the Japanese encephalitis vaccination.

Japanese encephalitis can cause severe complications or death. Complications of Japanese encephalitis include permanent injury to your brain or nervous system.

About half of the people who survive symptomatic Japanese encephalitis experience complications.

You can visit the Department of Health and Aged Care (Opens in new tab)for more information about Japanese encephalitis.

There are some areas where it is more likely that mosquitoes are carrying JEV.

For information on where you live, or if you are travelling, visit the relevant state or territory's website:

• Australian Capital Territory (Opens in new tab)
• New South Wales (Opens in new tab)
• Northern Territory (Opens in new tab)
• Queensland (Opens in new tab)
• South Australia (Opens in new tab)
• Tasmania (Opens in new tab)
• Victoria (Opens in new tab)
• Western Australia (Opens in new tab)

For more information on staying safe from Japanese encephalitis while travelling, you can:

• check the Smartraveller website (Opens in new tab)
• read more about travel vaccinations

If you need advice on Japanese encephalitis, call healthdirect on 1800 022 222 to speak with a registered nurse, 24 hours, 7 days a week (known as NURSE-ON-CALL in Victoria).

Languages other than English

The Department of Health, Disability and Ageing (Opens in new tab) has Japanese encephalitis resources in many community languages.

The Northern Territory Government (Opens in new tab) also offers Japanese encephalitis information in other languages.

Information for Aboriginal and/or Torres Strait Islander peoples

The Department of Health, Disability and Ageing (Opens in new tab) has Japanese encephalitis resources for Aboriginal and/or Torres Strait Islander people.