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16 May 2011

Mosquito-borne disease risk extends to south-central regions of WA

Following new detections of activity of Murray Valley encephalitis (MVE) virus and the closely-related Kunjin virus in the Midwest, Wheatbelt and Goldfields regions the Department of Health has extended its advice to people living and travelling anywhere north or east of Perth in WA to take extra care against mosquito bites.

Six Western Australians have been diagnosed with encephalitis (a serious inflammation of the brain) due to MVE virus infections contracted in northern and central WA this season. One person has died and several others remain very ill in hospital. Other possible cases of MVE infection are being investigated.

Department of Health Medical Entomologist Sue Harrington said that the Department's surveillance program (undertaken by The University of Western Australia) had detected activity of the rare, but potentially fatal, MVE and Kunjin viruses in the Kimberley, Pilbara, Gascoyne, Goldfields, Midwest and central Wheatbelt regions, indicating that virus activity was likely to be widespread.

"Murray Valley encephalitis virus and Kunjin virus are carried by mosquitoes, and while the risk of being infected and becoming unwell is low, the illnesses can be severe and people should take sensible precautions to avoid mosquito bites," Ms Harrington said.

"In some locations, mosquito numbers are quite low, but it is still important to take measures to avoid mosquito bites," she said.

"Initial symptoms of MVE include fever, drowsiness, headache, stiff neck, nausea and dizziness and people experiencing these symptoms should seek medical advice quickly. In severe cases, people may experience fits, lapse into a coma, and may be left with permanent brain damage or die.

"In young children, fever might be the only early sign, so parents should see their doctor if concerned, particularly if their child experiences drowsiness, floppiness, irritability, poor feeding, or general distress.

"Kunjin virus usually causes milder illness than MVE virus, but in rare cases, it also causes severe symptoms, including headache, neck stiffness, fever, delirium and coma."

Ms Harrington said that anyone experiencing these symptoms should seek medical advice quickly.

In addition, cases of Ross River and Barmah Forest virus diseases continue to be notified in people from across much of WA.

"The illnesses caused by Ross River and Barmah Forest viruses are similar, with symptoms including painful joints, aching muscles, lethargy, fever, headache and skin rashes, and symptoms may last from days to months."

"There are no specific cures or vaccines for any of these mosquito-borne diseases so it is very important that people take care to prevent being bitten by mosquitoes."

Ms Harrington said controlling mosquitoes in most rural regions of WA was generally not possible because of the large size and inaccessibility of natural mosquito breeding habitat.

People do not need to alter their plans to visit locations in the Kimberley, Pilbara, Gascoyne, Midwest, Wheatbelt or Goldfields regions, but it is important to avoid mosquito bites by taking a few simple steps, such as:

  • avoiding outdoor exposure from dusk and at night
  • wearing protective (long, loose-fitting) clothing when outdoors
  • applying a personal repellent containing diethyl toluamide (DEET) or picaridin to exposed skin or clothing. The most effective and long-lasting formulations are lotions or gels. Most natural or organic repellents are not as effective as DEET or picaridin or need to be reapplied more frequently
  • ensuring insect screens are installed and completely mosquito-proof: use mosquito nets and mosquito-proof tents
  • ensuring infants and children are adequately protected against mosquito bites, preferably with suitable clothing, bed nets or other forms of insect screening

Media contact: (08) 9222 4333

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