Japanese encephalitis virus

Japanese encephalitis (JE) is a rare but serious disease caused by the Japanese encephalitis virus.

In humans

The virus is transmitted to humans through bites from Culex mosquitoes, which have been infected themselves by biting an infected animal – most often waterbirds.

Most people with Japanese encephalitis virus infection do not experience any illness. There may be mild symptoms such as fever and headache. However, a small proportion will have encephalitis (inflammation of the brain), which can cause permanent damage to the nervous system or death.

There is no specific treatment for infection with JE virus.

Vaccination against JE virus is recommended for persons at highest risk of infection, including certain occupations.

People should take steps to protect themselves and their families against mosquito-borne diseases.

For more information visit the SA Health website:

In animals

Japanese encephalitis virus has been detected in a number of commercial piggeries in South Australia, following detections in Victoria, New South Wales and Queensland. An additional case has been detected in an alpaca.

The natural lifecycle of JE is between waterbirds and mosquitoes, which may on occasion spill over to pigs and horses and rarely other animals.

Domestic and commercial pig and horse owners are urged to be on alert for JE.

  • Control mosquitoes on your property. Eliminate breeding areas and use chemicals responsibly.
  • Prevent mosquito bites to your pigs and horses, and protect yourself, your family and your staff.
  • Report if you suspect the virus in your animals. JE is a nationally notifiable disease and you must immediately call your private vet or the Emergency Animal Disease Watch Hotline on 1800 675 888.

For more information, visit the Department of Primary Industries and Regions (PIRSA) website.

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Page last updated 12 April 2022

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