Japanese encephalitis is a rare but serious illness caused by the Japanese encephalitis virus. It is spread to humans by infected mosquitoes.

Last updated: 07 February 2023

​What are the symptoms of Japanese encephalitis?

Most people who get Japanese encephalitis do not have any symptoms.

Some people may get symptoms such as:

  • fever
  • headache
  • vomiting

People with a severe infection (1 in every 250 people) may get symptoms such as:

  • neck stiffness
  • disorientation
  • tremors
  • coma
  • seizures
  • paralysis

If you get these symptoms, contact a doctor right away, or Healthdirect on 1800 022 222 or in an emergency call Triple Zero (000) or visit your nearest emergency department.

Among those who get a serious illness, some may have lifelong neurological complications or even death.

If you get symptoms, they can appear 5 to 15 days after getting bitten by infected mosquitoes.

How is the Japanese encephalitis virus spread?

It is spread when a mosquito bites an animal (such as pigs or waterbirds) that has the Japanese encephalitis virus and then this mosquito bites a human.

Humans are not able to give Japanese encephalitis virus to other humans. Humans cannot get Japanese encephalitis virus by touching an infected animal or eating animal products.

Who has a higher chance of getting the Japanese encephalitis virus?

Those who are more likely to get Japanese encephalitis virus are:

  • people who work or do outside activities (e.g., camping, fishing, hiking, gardening) in high-risk areas.
  • people working at and, or living close to piggeries (if infected by a mosquito, pigs can get high levels of virus, and infect more mosquitoes if bitten)

How do you know if you have Japanese encephalitis?

If you have the symptoms listed above a doctor may run a test to detect a virus or measure levels of antibodies to Japanese encephalitis in samples of blood or spinal fluid.

How is Japanese encephalitis treated?

There is no specific treatment for Japanese encephalitis. Patients with symptoms often need hospital support and sometimes intensive care.

How do I avoid the Japanese encephalitis virus?

The best way to avoid Japanese encephalitis is to not get bitten by mosquitoes.

Protect yourself:

  • use insect repellent. The best mosquito repellents have diethyltoluamide (DEET), picaridin, or oil of lemon eucalyptus
  • wear long, loose fitting and light-coloured clothing when outside
  • wear covered shoes
  • do not spend lots of time outside at dawn and dusk when mosquitoes are most active
  • cover all windows, doors, vents, and other entranced with insect screens
  • remove any containers that hold water where mosquitoes may breed
  • use insecticide sprays, vapour dispensing units (inside), and mosquito coils (outdoors) to clear rooms and repel mosquitoes from an area
  • use mosquito nets or screens

Japanese encephalitis vaccination

The Japanese encephalitis vaccine is safe and effective. People aged 2 months and older can get the vaccine. Vaccination against Japanese encephalitis is recommended for those at the highest risk of getting Japanese Encephalitis.

Learn more about who can get a free vaccine.

Vaccine is also recommended to some people travelling to high-risk countries.

If you think you might be able to get the vaccine, talk to your local doctor.

Current as at: Tuesday 7 February 2023
Contact page owner: One Health