The Western Australia Health Department has issued a Ross River Virus (RRV) alert for the South West Region.
The alert has been brought forward this year due to increased numbers of mosquitoes capable of carrying RRV. Department of Health Medical Entomologist Dr Mike Lindsay said that the higher than usual numbers are "due to recent good winter rains and high tides".
Increased numbers of mosquitoes have also been detected in the Peel Region igniting fears that if desirable breeding conditions remain the virus may spread Perth's southern suburbs.
The similar mosquito borne virus, Barmah Forest virus (BFV) will also be prevalent in the South West this year. Both viruses have very similar symptoms which can include painful or swollen joints, sore muscles, skin rashes, fever, chronic fatigue and headaches. The viruses can last for weeks or months and can only be diagnosed by a blood test.