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Japanese encephalitis

6-minute read

There have been recent reports of Japanese encephalitis in Australia. Visit the Department of Health website for the latest updates on this health alert.

Key facts

  • Japanese encephalitis is a serious disease caused by the Japanese encephalitis virus (JEV).
  • Humans can catch JEV if they are bitten by infected mosquitoes.
  • Only about 1 out of 100 people who catch JEV will experience symptoms.
  • For people who have symptoms, Japanese encephalitis can cause death or permanent injury to the brain and nervous system.
  • You can reduce your chance of catching Japanese encephalitis by avoiding mosquito bites and getting vaccinated against JEV.

What is Japanese encephalitis?

Japanese encephalitis is a serious disease caused by the Japanese encephalitis virus (JEV). It is endemic (regularly found) in parts of Asia and the Torres Strait region of Australia. Most people infected with Japanese encephalitis do not experience symptoms. However, those who do may develop severe illness.

How can I catch the Japanese encephalitis virus?

JEV spreads to humans via infected mosquitoes. Animals such as pigs can also catch JEV, but they cannot transfer the virus to humans. You cannot catch JEV through contact with infected people or animals. You also cannot catch it by eating meat from an infected animal.

What are the symptoms of Japanese encephalitis?

Only about 1 out of 100 people with Japanese encephalitis will experience any symptoms.

You may notice symptoms about 5 to 15 days after being bitten by a JEV-infected mosquito.

Symptoms you may notice include:

CHECK YOUR SYMPTOMS Use the Symptom Checker and find out if you need to seek medical help.

When should I see my doctor?

If you have recently been in an area with reports of JEV, and you experience sudden fever, severe headache, vomiting, confusion, paralysis or seizures, visit your nearest emergency department or call triple zero (000).

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

How is Japanese encephalitis diagnosed?

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, you may need a blood test or lumbar puncture (spinal tap). These tests can confirm the diagnosis.

Japanese encephalitis is a notifiable disease. This means that a doctor who diagnoses Japanese encephalitis needs to report the case to local health authorities, who can take steps to control an outbreak.

How is Japanese encephalitis treated?

There is no specific medicine or treatment available to treat Japanese encephalitis. Antibiotics will not help you recover because this illness is caused by a virus, not bacteria.

Strategies to try to relieve your symptoms at home include:

  • getting plenty of rest
  • drinking enough fluid
  • taking paracetamol to relieve fever

If your symptoms are severe or you experience complications, you may need to be treated in hospital.

Can Japanese encephalitis be prevented?

There are 2 ways that you can prevent Japanese encephalitis:

  • Avoid being bitten by mosquitoes, especially in areas where JEV is common.
  • Receive a vaccine against JEV.

Here are some strategies that you can use to protect yourself from mosquito bites:

  • Reduce skin exposure. Wear loose-fitting, long-sleeved shirts and long pants, socks and enclosed footwear.
  • Use insect repellent. Choose products that contain diethyltoluamide (DEET), picaridin or lemon eucalyptus oil — these are most effective against mosquitoes. Check the product label for information about reapplication times.
  • Stay and sleep in rooms or tents that have flyscreens or mosquito nets.
  • Do not leave water containers open. Mosquitoes use stagnant water to breed.

Visit Better Health Channel's Beat the Bite page for more tips.

JEV vaccination

Vaccination is a safe and effective way to reduce your chance of catching JEV. People who spend a month or more in Asia or the Torres Strait region of Australia during the wet season should get vaccinated against JEV. Vaccination is also recommended for laboratory workers who may be exposed to JEV at work.

Due to the recent outbreak of JEV in Australia, people who look after or work with pigs should receive JEV vaccination. People who work with mosquitoes, such as environmental health workers, should also be vaccinated against JEV.

Visit the Department of Health website for the latest information about the JEV outbreak and vaccination recommendations.

How many types of vaccines are available?

Two types of vaccines against JEV are currently available in Australia.

When to get vaccinated?

Before you spend 1 month or more in Asia or the Torres Strait region of Australia in the wet season. Ask your doctor, travel clinic or local immunisation service if you're not sure whether you should get vaccinated.

How many doses are required?

1 dose, or 2 doses given 28 days apart, depending on the type of vaccine recommended for you.

How is it administered?

Injection

Is it free?

No — there is a cost.

Find out more on the Department of Health website and the National Immunisation Program Schedule, and ask your doctor if you are eligible for additional free vaccines based on your situation or location.

Common side effects

The vaccine is very safe. Side effects are mild and temporary and may include a sore arm, swelling where the injection went in, headache or fatigue.


Are there complications of Japanese encephalitis?

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

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

Resources and support

Visit the Department of Health website for more information about Japanese encephalitis, the recent JEV outbreak and current vaccination recommendations.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: March 2022


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