18 June 2018

Increased mosquito-borne disease risk in central and northern Western Australia

The Department of Health is warning residents and travellers in central and northern Western Australia, particularly in coastal areas, to take precautions to avoid mosquito bites.

The warning follows recent heavy rainfall in some areas of the Gascoyne and Pilbara regions that has the potential to result in significant mosquito breeding.

Managing Scientist, Dr Michael Lindsay, said that the mosquito numbers were expected to rise in coming weeks, bringing potential for a substantial increase in the activity of mosquito-borne viruses including Ross River virus (RRV).

“Symptoms of RRV infection can last for weeks or months, and include painful or swollen joints, sore muscles, skin rashes, fever, fatigue and headaches,” he said.

“The only way to diagnose this and other mosquito-borne viruses is by visiting a doctor and having a specific blood test.”

The warning also follows continued evidence of activity of Murray Valley encephalitis (MVE) and Kunjin virus across the Kimberley and Pilbara regions.

“While no human cases of either disease have been reported in WA this year, evidence of both viruses continues to be detected in sentinel chicken flocks, which are used as an early warning system,” Dr Lindsay said.

“As with RRV, both viruses are only carried by mosquitoes, and while the risk of being infected and becoming unwell is low, the symptoms associated with both MVE and Kunjin diseases can be seriously debilitating, and in the case of MVE, potentially fatal.”

Initial symptoms of MVE include fever, drowsiness, headache, stiff neck, nausea and dizziness. 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.

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

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

People do not need to alter their travel plans to affected regions but it is important to avoid mosquito bites. Fight the Bite when camping, fishing or undertaking other outdoor activities by taking these few simple steps:

  • avoid outdoor exposure around dawn and early evening
  • wear protective (long, loose-fitting, light-coloured) clothing when outdoors
  • apply an effective personal repellent containing diethyltoluamide (DEET) or picaridin to exposed skin and always follow the label instructions
  • use mosquito coils and mosquito lanterns and apply barrier sprays containing bifenthrin in patio and outdoor areas around houses
  • ensure insect screens are installed and in good condition on houses and caravans
  • use mosquito nets and mosquito-proof tents when camping
  • ensure infants and children are adequately protected against mosquito bites, preferably with suitable clothing, bed nets or other forms of insect screening.

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.

For more information about mosquito prevention visit HealthyWA (external site).


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