People in Western Australia's South West region are being warned to avoid mosquito bites after this season's first detection of Ross River virus in the insects.
The Health Department says its mosquito and virus surveillance program has detected the virus at coastal mosquito breeding sites in the region.
Symptoms include painful or swollen joints, sore muscles, skin rashes, fever, fatigue and headaches.
The department says symptoms can last for weeks or months, and the only way to properly diagnose the virus is by having a specific blood test.
Michael Lindsay, the managing scientist of environmental health hazards at the Health Department, says there is no cure for Ross River virus so it is important that people take care to prevent bites.
"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", he said.
Dr Lindsay says activity could spread to other regions where mosquito populations had already established after recent rain.
He says local government mosquito management programs had been under way since August in some areas and would continue in regions at risk of the virus, but could not be solely relied upon.
The warning comes as experts from around Australia gather in Mandurah, south of Perth, this week for a mosquito management course.
The course will provide participants with knowledge and skills required to develop and implement mosquito management programs in their own areas.Topics covered include mosquito biology, mosquito-borne diseases and methods of controlling mosquitoes.