WA at increased risk of mosquito-borne diseases

The Health Department have warned people in WA about increased risk of mosquito-borne diseases.
The Health Department have warned people in WA about increased risk of mosquito-borne diseases.

The Department of Health has warned people in WA to take precautions against biting insects and mosquitoes following the widespread rainfall and recent flooding across the state.

Managing scientist environmental health hazards Dr Michael Lindsay said the wet weather and flooding had created ideal conditions for breeding of mosquitoes and other biting insects across much of the state.

Dr Lindsay said while local government mosquito management programs were in place, it was not realistic or logistically feasible to keep mosquitoes and biting flies below nuisance levels when such vast areas of WA were affected with the recent weather conditions.

“Increased mosquito activity is likely to result in an increased risk of the mosquito-borne diseases Ross River virus and Barmah Forest virus.”

A Department of Health spokesperson said since July last year, there were 394 cases of Ross River Virus recorded in WA – 186 of those cases were from the South West region.

“By comparison, the current year has seen more mosquito and virus activity but is following the long term average trend, as was predicted in the last couple of years,” they said.

“Other regions of WA are also following the long term average trend, with increased mosquito and virus activity during summer months.”

The spokesperson said recent heavy rainfall could result in spikes in the mosquito populations around WA, however the disease case numbers do not indicate a Ross River virus outbreak conditions.

UWA School of Medicine clinical professor David Smith said there were only two mosquito-borne viruses which have been shown to infect people in the South West: Ross River virus and Barmah Forest virus.

Professor Smith said Ross River virus illness was about 10 to 20 times as common as the Barmah Forest virus illness, and between 400 and 1400 cases were notified each year, most of which were in the South West.

“As you know the weather conditions this year are not good in terms of the risk to people, so we need to be extra careful about mosquito exposure,” he said.

Professor Smith said there were no specific antiviral therapies for any of the mosquito-borne viruses that were seen in WA and there were no vaccines available.

“So avoiding getting bitten is really the only option,” he said.

Professor Smith said treatment of the symptoms depended on how bad the illness was.

“For Ross River virus treatment usually involved rest, pain killers and anti-inflammatory drugs, with gentle exercise,” he said.

”Most people with Ross River virus illness gradually recover from their illness over one to three months, but some have symptoms (especially tiredness, sore muscles and joint pains) for many months or years.”  

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

ANU Medical School of Infectious Diseases physician and microbiologist professor Peter Collignon said people had to wait until their body fought off the infection via their own white cells, antibodies etc and then wait for the virus and symptoms to disappear. 

“Most people who get infected have no symptoms. For Ross River most with symptoms will be unwell for a few weeks,” he said.

“But there are some who have much longer ongoing symptoms – sometimes a year of more (although luckily they are only a small proportion of those infected – but a major problem if you are one of those people,” he said.

How to avoid mosquito bites

Dr Lindsay said people throughout WA should take extra precautions to avoid being bitten by mosquitoes and flies:

People should avoid outdoor exposure particularly around dawn and dusk (and the first few hours after dark), wear protective clothing when outdoors such as long, loose-fitting and light coloured clothes.

A personal repellent containing 20 per cent 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.

Wear head nets if outdoors

Ensure insect screens are installed and in good condition – the use of bed nets when sleeping will offer further protection

Use mosquito nets or mosquito-proof tents when camping or sleeping outdoors

Ensure infants and children are adequately protected against biting insects, preferably with suitable clothing, bed nets or other forms of insect screening.

The recent rainfall 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 such as:

Dispose of all containers which hold water.

Stock ornamental ponds with fish and keeping 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 and 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.


Discuss "WA at increased risk of mosquito-borne diseases"

Please note: All comments made or shown here are bound by the Online Discussion Terms & Conditions.