Residents and visitors to the Goulburn Valley area in northern Victoria are being warned to protect themselves from mosquito bites following detection of West Nile or Kunjin virus in Shepparton.
Victoria's Chief Health Officer Professor Charles Guest said the virus had been detected in a sentinel chicken flock at Shepparton.
The Kunjin virus is in the same family as Murray Valley Encephalitis (MVE), and can cause mild but more significant illness than other viruses associated with mosquitoes, such as Ross River Virus.
The sentinel chicken surveillance program - during which chickens are regularly tested for the presence of a range of mosquito-borne infections - serves as an early warning system for potential human cases.
Sentinel chicken flocks have been used since the last confirmed human case of MVE was reported in 1974, when a large outbreak occurred throughout much of south eastern Australia.
Professor Guest said no viruses had been detected in the other 12 Victorian flocks this season, but testing continues.
Symptoms for Kunjin virus are fever, headache, aching muscles and/or joints and fatigue. People experiencing symptoms should seek immediate medical attention from their GP or their local hospital. Onset of symptoms may be from 2 to 14 days following a mosquito bite.
Kunjin virus is a rare cause of infection, with fewer than 10 cases each year.
"Recent rain and relatively warm weather has created conditions ideal for mosquito breeding and we have seen a significant increase in mosquito numbers as a result," he said.
"Taking measures to avoid bites is a critical step to protect yourself and your family against mosquito-borne diseases."
Across Victoria enhanced control measures have been introduced with seven councils previously involved in control program now able to scale up their activities through additional staff and the purchase of high capacity and specialised spray equipment and vehicles.
Eleven new councils are now undertaking control measures for the first time in their municipalities through the treatment of more mosquito breeding sites.
Professor Guest says the environmental conditions over the next few weeks may continue to provide ideal breeding conditions for mosquitoes.
"Simple precautions can help protect against mosquitoes," he said.
"Mosquitoes are at their most active at dawn and dusk, although some species can be present and bite throughout the day.
"Householders should ensure that insect screens fitted to doors and windows are in good condition.
"Visitors and residents are encouraged to wear long, light coloured loose-fitting clothing and use a suitable insect repellent containing picaridin or DEET as an active ingredient on exposed skin areas.
"Mosquito numbers can be reduced by getting rid of stagnant water around the home or campsites. Mosquitoes will breed in any receptacle that can hold water, including old tyres, unused fish ponds, unsealed water tanks and pot plant holders.
"As mosquitoes can hatch quickly, water containers around the home should be emptied at least once a week."
Reviewed 15 February 2017