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3 October 2011

Ross River virus disease risk in south-west

The Department of Health today reminded people living or holidaying in the south-west of WA to avoid mosquito bites following the first detection of Ross River virus (RRV) activity for the season.

Department of Health Medical Entomologist Sue Harrington said the Department's mosquito and virus surveillance program (undertaken by The University of Western Australia) had detected RRV for the first time this season at mosquito monitoring sites in the Leschenault region.

Ms Harrington said repeated high tides and rainfall had resulted in the breeding of saltmarsh mosquitoes, which were efficient carriers of RRV. Mosquito management being undertaken by the local governments in collaboration with the Department of Health has been underway since September to reduce mosquito numbers and the risk of RRV and Barmah Forest virus (BFV).

"However, it is not realistic to rely on mosquito management programs to keep mosquitoes below nuisance levels, especially when unfavourable environmental conditions reduce the effectiveness of control methods. Therefore, people need to take their own precautions to avoid mosquito bites," Ms Harrington said.

"Although the initial detection of virus has been in the Leschenault region, people living near tidal saltmarshes and seasonal brackish and freshwater wetlands in other coastal parts of the south-west are also likely to be at risk in coming weeks. The risk may also spread to parts of the Perth metropolitan area if conditions favour continued mosquito breeding."

Most of the types of mosquito that carry RRV and BFV in the south-west and Perth breed in natural environments but they can also breed in water-holding containers, rainwater tanks and other receptacles around houses and the urban environment.

People can help reduce RRV and BFV risks in their community by ensuring they are not breeding mosquitoes around their home or work place.

Symptoms of RRV and BFV include painful or swollen joints, sore muscles, skin rashes, fever, fatigue and headaches.

Symptoms can last for weeks or months and the only way to properly diagnose the viruses is by having a specific blood test.

There are no cures or vaccines for these viruses so it is very important that people take care to prevent being bitten by mosquitoes.

People do not need to alter their plans to visit the south-west as a result of this warning, but it is important to avoid mosquito bites by taking a few simple steps, such as:

  • avoiding areas of high mosquito activity, especially around dawn and dusk
  • wearing protective (long, loose-fitting) clothing when outdoors
  • using a personal repellent containing diethyl toluamide (DEET) or picaridin. 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. Only infant-strength repellents should be used on small children.
Media contact: 9222 4333

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