Summary

  • West Nile virus is a viral infection spread by  mosquito bites.
  • A strain of the West Nile virus, called West Nile virus/Kunjin, is found in parts of Australia, particularly the Northern Territory and northern Western Australia.
  • Infection may be asymptomatic or can cause mild flu-like symptoms.
  • In very rare cases, infection can lead to serious complications such as meningitis and encephalitis.
  • Reduce the chance of being bitten by mosquitoes by wearing long, loose-fitting, light coloured clothing and use effective insect repellent in mosquito-prone areas.

About West Nile virus/Kunjin

West Nile virus is a viral infection carried by mosquitoes. It belongs to a group of viruses called flaviviruses. A person infected with the virus may have no symptoms. About 20% of people infected develop mild flu-like symptoms such as fever, fatigue and aching muscles. In rare cases, the West Nile virus can lead to serious complications such as meningitis (infection or inflammation of membranes surrounding the brain) or encephalitis (inflammation of the brain). West Nile virus can be found in Africa, Europe, the Middle East and in the USA.

West Nile virus/Kunjin is a strain of West Nile virus and is found in parts of Australia, particularly the Northern Territory and northern Western Australia. No other subtypes of West Nile virus are found in Australia. West Nile virus/Kunjin is less virulent (severe) than other strains of West Nile virus. Symptoms can appear from 7 to 28 days after becoming infected. However, many people infected with West Nile virus/Kunjin will never develop symptoms. People with antibodies to West Nile virus/Kunjin may be immune to infection with West Nile virus. 

When in mosquito-prone areas, wear long, loose-fitting, light coloured clothing and use insect repellent containing DEET or Picaridin to help reduce the chance of being bitten by mosquitoes.

Symptoms of West Nile virus/Kunjin

Many people infected with West Nile virus/Kunjin show no symptoms. 

If symptoms occur, they can include:

  • fever
  • headache
  • muscle aches 
  • lethargy or fatigue.

In very rare cases (less than 1%), the infection can lead to serious complications. This includes meningitis (infection or inflammation of membranes surrounding the brain) or encephalitis (inflammation of the brain). These conditions may result in death or serious disability. 

If symptoms of meningitis or encephalitis occur, please seek medical attention immediately. These symptoms include: 

  • severe headaches
  • neck stiffness
  • sensitivity to bright light (photophobia)
  • seizure or fits (especially in young children)
  • drowsiness
  • confusion. 

Mosquitoes spread West Nile virus/Kunjin

People can be infected with West Nile virus/Kunjin when they are bitten by a mosquito that is carrying the virus. Throughout Australia, Culex annulirostris is the most important mosquito species that can carry this virus. This mosquito breeds in fresh water and is most active at dusk and dawn. Mosquitoes can pick up the virus when feeding on water birds such as herons. 

There is no evidence that West Nile virus/Kunjin can be spread directly from one person to another.

West Nile virus/Kunjin is rare in Australia 

West Nile virus/Kunjin disease is found in parts of Australia, particularly the Northern Territory and northern Western Australia. The virus has been detected in regional Victoria. However, it is considered rare with 43 cases reported throughout Australia since 1991 and only two cases reported in Victoria since 2010. 

Blood tests will show if you have West Nile virus/Kunjin 

Blood tests can reveal if a person has been infected with West Nile virus or West Nile virus/Kunjin recently or in the past.

Treatment for West Nile virus/Kunjin

There is no specific treatment available for West Nile virus/Kunjin. Treatment aims to support the patient and ease the symptoms while their body fights the infection. Your doctor will decide with you what treatment is best suited to your situation. Sometimes people may need hospital care, depending on the severity of the infection and if complications develop.

Preventing West Nile virus/Kunjin disease

There is no preventive vaccine available, your only protection against West Nile Virus/Kunjin is to avoid mosquito bites.

To reduce the risk of infection: 

  • Wear long, loose-fitting, light coloured clothing and use effective insect repellents that contain DEET or Picaridin applied regularly, according to the manufacturer’s instructions.
  • Avoid mosquito-prone areas, especially at dusk and dawn when mosquitoes are more active and likely to bite.
  • Ensure that your accommodation has fly screens properly fitted to windows and external doors.
  • Reduce the number of potential mosquito breeding habitats around your home by ensuring no stagnant water is present. Containers holding water should be emptied and washed regularly.

Where to get help

References

More information

Infections

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This page has been produced in consultation with and approved by: Department of Health and Human Services - RHP&R - Health Protection - Communicable Disease Prevention and Control Unit

Last updated: November 2020

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