21 March 2023

Recent Japanese encephalitis virus now detected in Kimberley region

The Department of Health is urging residents and travellers in the Kimberley region to avoid mosquito bites following evidence of recent Japanese encephalitis virus (JEV) activity in the area.

JEV activity has been identified through the Department of Health’s sentinel chicken surveillance program, which acts as an early warning system for mosquito-borne virus disease.

The positive samples were collected in February 2023 from chicken flocks in Kununurra and Wyndham in the Kimberley, indicating infection occurred in the last two months. This, combined with samples from pigs reported last week, indicates ongoing risk of JEV infection in the Kimberley.

JEV is transmitted through the bite of an infected mosquito and can lead to Japanese encephalitis, a vaccine-preventable disease.

Department of Health’s Acting Director of Communicable Disease Control, Dr Jelena Maticevic said the JEV activity in the Kimberley represented a significant risk to human health.

“Most people infected will have no or very mild symptoms and will fully recover, however, a small percentage develop severe illness including an encephalitis (brain inflammation), which can lead to serious complications and death,” she said.

“Anyone who develops a sudden onset of fever, headache, vomiting, seizures or disorientation should seek urgent medical attention.”

There have been 45 human cases of the mosquito-borne disease JE reported in Australia since January 2021, from New South Wales, Queensland, South Australia, Victoria and the Northern Territory. Sadly, seven people have died.

There have been no cases of Japanese encephalitis reported in people in WA to date.

Children under five years of age and older people who are infected with JEV are at a higher risk of developing more severe illness.

“Fortunately, there is a vaccine against Japanese encephalitis, which is available through regional health services to those at highest risk in the Kimberley.

“It is now more important than ever that people take measures to avoid mosquito bites to prevent infection.

“Avoiding mosquito bites will also protect against other mosquito-borne diseases for which there is no vaccine, including Murray Valley encephalitis”.

The Department of Health has recently detected widespread evidence of Murray Valley encephalitis virus and Kunjin virus activity in the Kimberley region, and evidence of Murray Valley encephalitis virus in the Pilbara.

The Department of Health continues to undertake enhanced surveillance in the Kimberley and Pilbara for mosquito-borne diseases.

Mosquitoes may carry viruses that can make people seriously ill. Fight the Bite (HealthyWA) - take the following simple steps to avoid being bitten:

  • Cover up while outside - wear loose, long-sleeved, light-coloured clothing, particularly at dawn and dusk when mosquitoes are most active.
  • Ensure infants and children are adequately protected against mosquito bites, preferably with suitable clothing, shoes/socks, bed nets or other forms of insect screening.
  • Apply mosquito repellent, containing picaridin, DEET or oil of lemon eucalyptus (OLE – also known as PMD), evenly to all areas of exposed skin. Read the instructions to find out how often you should reapply repellent.
  • Mosquito wristbands and patches are not recommended as there is no evidence that these provide good protection against mosquito bites.
  • Avoid outdoor exposure, particularly at dawn and early evening.

You can also limit the number of mosquitoes in and around your home by:

  • Cutting your grass often and keep it short to minimise mosquitoes seeking shelter around your home.
  • Applying a residual surface spray (containing bifenthrin) to outdoor walls, patios etc where mosquitoes might land – this will kill them. You can buy these products from hardware stores.
  • Removing water holding containers from around the home and garden to ensure mosquitoes do not breed in your own backyard.
  • Ensuring insect screens are installed and in good condition on houses and caravans.
  • Using mosquito nets and mosquito-proof tents if sleeping outside.
  • Using mosquito coils and mosquito lanterns.

JEV is a nationally notifiable disease in both humans and animals.

More information about vaccination and mosquito prevention is available online:

Japanese encephalitis (HealthyWA)

Read more about JEV in humans (healthyWA) and animals (external site)


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