Ross River Virus Risk For Perth, South-West

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Ross River Virus

The Department of Health is reminding people living or holidaying in the South-West of WA or the metropolitan area to take care against mosquito bites following an increase in reported cases of Ross River Virus (RRV) in recent weeks.

Medical Entomologist Dr Michael Lindsay said 125 cases of RRV had been reported in WA since the beginning of October, compared to 77 cases for the same period last year.

"Over the past three months our surveillance program has detected mosquitoes infected with RRV in the South-West, particularly in the Peel region, and we now have 40 confirmed cases of the disease from this area compared to nine cases for the same period last year," he said.

"A further 45 cases are from Perth and smaller clusters have also been reported from the Midwest, Esperance and Kimberley regions."

Dr Lindsay said above average late spring rain and regular high tides flooding saltmarsh mosquito breeding sites had favoured mosquito breeding and the mild start to summer had assisted survival of the adults.

Another similar mosquito-borne virus, Barmah Forest Virus (BFV), has also been active in some areas of the South-West in the past few weeks.

Dr Lindsay said mosquito management programs by local governments and the Department of Health were continuing in areas with a recognised RRV risk.


"However, it is not realistic to rely on these programs to keep mosquitoes below nuisance levels, especially when unfavourable environmental conditions reduce the effectiveness of control methods, so people need to take their own precautions to avoid being bitten," he said.

"At the moment, coastal communities in the South-West within 3km of tidal saltmarshes and seasonal brackish and freshwater wetlands are likely to be at greatest risk.

"However, there is also a risk in Perth, especially the outer metropolitan area and suburbs with large areas of natural mosquito breeding habitat, if environmental conditions continue to favour mosquito breeding in the coming weeks."

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 around houses and other buildings.

People can help reduce RRV and BFV risks in their community by emptying these containers, which will help to ensure they are not breeding mosquitoes around their home or work place.

RRV and BFV cause painful or swollen joints, sore muscles, skin rashes, fever, chronic fatigue and headaches.

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

There are no specific 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, but it is important to avoid mosquito bites by taking a few simple steps, such as: