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21 October 2013

Ross River virus disease risk increases in south-west

The Department of Health is warning residents and visitors in the southwest of the State to avoid mosquito bites following the detection of Ross River virus (RRV) activity in mosquito populations for the first time this season.

The Department of Health's Managing Scientist of Environmental Health Hazards, Dr Michael Lindsay said the Department's mosquito and virus surveillance program (undertaken by the University of Western Australia) has now detected RRV at coastal mosquito breeding sites in the south-west.

Symptoms of RRV 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 is no cure for RRV so it is very important that people take care to prevent being bitten by mosquitoes.

"Above average rainfall this spring has enabled breeding of mosquitoes in large numbers in many coastal and inland areas of the south-west and wheatbelt", Dr Lindsay said.

The Department now has evidence that RRV is active in coastal mosquito populations. This activity may also spread to other regions where mosquito populations have already established as a result of the recent rains.

Local Government mosquito management programs have been underway since August in some areas and will continue in regions with a recognised risk of RRV.

"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," Dr Lindsay said.

People living in or travelling to mosquito-affected areas in the southwest of WA should take extra precautions, such as:

  • avoiding outdoor exposure particularly around dawn and dusk (and the first few hours after dark)
  • wearing protective (long, loose-fitting, light coloured) clothing when outdoors
  • applying a personal repellent containing 20% diethyl toluamide (DEET) or picaridin to exposed skin or clothing. The most effective and long-lasting formulations are lotions or gels. Natural or organic repellents may not be as effective as DEET or picaridin, or may need to be reapplied more frequently
  • ensuring insect screens are installed and in good condition. The use of bed nets will offer further protection
  • using mosquito nets or mosquito-proof tents when camping or sleeping outdoors
  • ensuring infants and children are adequately protected against mosquito bites, preferably with suitable clothing, bed nets or other forms of insect screening.

With summer approaching, it is also a timely reminder for residents to minimise mosquito breeding around the home by taking some simple steps to remove or modify breeding sites. Residents should:

  • Dispose of all containers which hold water
  • Stock ornamental ponds with fish and keep vegetation away from the water's edge
  • Keep swimming pools well chlorinated, filtered and free of dead leaves
  • Fill or drain depressions in the ground that hold water
  • Fit mosquito proof covers to vent pipes on septic tank systems. Seal all gaps around the lid and ensure leach drains are completely covered
  • Screen rainwater tanks with insect proof mesh, including inlet, overflow and inspection ports
  • Ensure guttering does not hold water
  • Empty pot plant drip trays once a week or fill them with sand
  • Empty and clean animal and pet drinking water bowls once a week.

Media contact: (08) 9222 4333

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