Residents and travelers to the Kimberley region of Western Australia are being warned by the Department of Health to take precautions against mosquito bites, following the detection of Japanese encephalitis virus (JEV) activity in the area.

The Department of Health's sentinel chicken surveillance program, which acts as an early warning system for mosquito-borne virus diseases, recently identified positive samples in February 2023 from chicken flocks in Kununurra and Wyndham, 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 region.

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."

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

No cases of Japanese encephalitis have been reported in WA to date. However, children under the age of five 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.

Dr Maticevic said 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," she said.

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.

To avoid being bitten by mosquitoes, the Department of Health recommends taking the following simple steps:

• Use insect repellents containing an effective ingredient such as DEET, picaridin or oil of lemon eucalyptus;
• Wear long, loose and light-coloured clothing when outdoors;
• Stay inside when mosquitoes are most active, particularly around dawn and dusk;
• Limit the number of mosquitoes in and around your home by eliminating standing water around the yard and house;
• Use fly screens to keep mosquitoes out of your house;
• Use air conditioning or mosquito nets if you are sleeping outdoors or in a poorly screened area; and
• If travelling overseas, seek advice from your doctor or travel clinic.

JEV is a nationally notifiable disease in both humans and animals. More information about vaccination and mosquito prevention is available online at HealthyWA and external sites.

The Department of Health urges all residents and travelers in the Kimberley region to take the necessary precautions to avoid mosquito bites and protect themselves and their families from the risk of JEV and other mosquito-borne diseases.