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13 February 2014

Increase in biting flies across regional Western Australia

The Department of Health is warning residents and travellers across various parts of regional Western Australia to take precautions against biting insects.

Department of Health Medical Entomologist, Dr Peter Neville said recent rainfall and flooding events combined with warm temperatures has led to an increase in the breeding of biting insects.

An increase in the number of March flies has been reported from various regions of Western Australia, including the northern Goldfields and Pilbara regions. At least one species of these biting flies (Mesomyia tryphera) has a bite that can cause serious allergic reactions in some people.

"Although March flies are not known to transmit diseases to humans in Australia, their bites can cause adverse allergic reactions, including skin redness and swelling. In rare cases, people may experience serious symptoms including hives, fever, wheezing and even anaphylaxis.," Dr Neville said.

 "People suffering from these more severe symptoms should seek medical attention quickly."

Widespread rainfall and flooding in parts of the Kimberley and Pilbara regions will also lead to increased mosquito breeding in the next few weeks, and an increased risk of transmission of mosquito-borne Ross River virus (RRV) and Barmah Forest virus (BFV).

Symptoms of infection with RRV and BFV include painful or swollen joints, sore muscles, skin rashes, fever, fatigue and headaches. There is no cure for these viruses and symptoms can last for weeks or months, making it essential to take care to avoid being bitten. 

"It is not possible to keep mosquitoes and other biting insects below nuisance levels across extensive rural areas of WA, especially when unfavourable environmental conditions reduce the effectiveness of control methods," Dr Neville said.

"It's important that people also take their own precautions to avoid biting insects."

People living or travelling throughout Western Australia should take extra precautions to avoid biting insects, including:

  • avoiding outdoor exposure if large numbers of biting insects are around—for mosquitoes this is particularly around dawn and dusk (and the first few hours after dark), but it may be at any time of day for March flies
  • wearing protective (long, loose-fitting, light coloured) clothing when outdoors (there is some evidence that March flies are attracted to blue colours, so avoid wearing blue coloured clothing if possible)
  • 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
  • wearing head nets if outdoors
  • 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 biting insects, preferably with suitable clothing, bed nets or other forms of insect screening.

Media contact: (08) 9222 4333

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