MOSQUITO-borne viruses is on the rise, with an increase in infection rates across the state's northern and central regions.
The Department of Health today upgraded its warning for people in the Kimberley, Pilbara and Gascoyne regions as reports of Ross River and Barmah Forest viruses continue to climb.
A surveillance program carried out by the University of WA has detected widespread activity of Murray Valley encephalitis and Kunjin viruses in several locations, although there is yet to be any reported infection.
Department medical entomologist Sue Harrington said the massive amounts of rain and subsequent flooding across the northern parts of WA had resulted in a large number of mosquitoes that could be carrying the viruses.
Ms Harrington said people most likely to be affected by Kunjin or MVE viruses were newcomers to affected regions, such as babies, young children, tourists or new employees, but anyone experiencing these symptoms should seek medical advice quickly.
A large number of Ross River cases have been found in people from the Kimberley and Pilbara regions, while cases of the Barmah Forest virus are also being reported from the Midwest region.
The illnesses caused by Ross River and Barmah Forest viruses are similar, with symptoms including painful joints, aching muscles, lethargy, fever, headache and skin rashes, and symptoms may last from days to months.
Ms Harrington said controlling mosquitoes in most rural regions of WA was generally not possible because of the large size and inaccessibility of natural mosquito breeding habitat.
She said people should not alter their travel plans through the region, but should ensure they take steps to ensure their exposure to mosquitoes is limited by wearing long, loose-fitting clothing, applying mosquito repellent and sleeping with the protection of mosquito nets.