South Australia's health chief has issued a public warning after the mosquito-borne Murray Valley encephalitis virus was detected at sites in the state's flood-hit regions.
SA Health said the virus, which can occasionally be fatal, was found last week in mosquitoes in monitoring traps in five River Murray council areas: Berri Barmera, Mid Murray, Renmark Paringa, Loxton Waikerie and Murray Bridge.
No cases have been reported in humans but the detections have come amid similar reports in New South Wales and Victoria.
Chief public health officer Nicola Spurrier urged the public to take precautions to avoid getting bitten.
"There has been a large increase of mosquito populations so far this season, making the need to protect ourselves even more important," Professor Spurrier said in a statement.
"The best protection … is to not get bitten in the first place.
"It is important South Australians remain vigilant and take simple steps to protect themselves against mosquito bites, including wearing long-sleeved, light-coloured clothing."
The last known human case of Murray Valley encephalitis virus (MVEV) in South Australia was in 2011, but the Japanese encephalitis virus (JEV) was identified last month in a man in the Riverland.
SA Health said the current mosquito season was "of particular concern", given the "very high" number of detections of the Ross River and Barmah Forrest viruses.
"Whilst many people with MVEV disease can have minimal symptoms, some people develop meningitis or encephalitis with symptoms including confusion, headaches, neck stiffness, tremors, drowsiness, and seizures," SA Health said.
"Occasionally the disease is fatal."
'Lots of viruses around'
Immunisation Coalition chairman Rod Pearce said the risk had been exacerbated by flooding, and would continue as the recovery effort increased in coming weeks and months.
"The risk of catching encephalitis or an illness from a mosquito bite is ever-present. South Australia's got issues with lots of viruses being around," Dr Pearce said.
"People are going to be travelling to the Riverland to help mop up after the floods … [and] we need to be careful.
"It is a challenge for South Australians to look after themselves when they're going to be helping friends, relatives or going to look after their own shack or house that's been flooded."
A JEV vaccine is available for those eligible, but there is neither a vaccine nor a cure for MVEV, SA Health said.
SA Health also recommended application of an insect repellent containing DEET, picaridin or oil of lemon eucalyptus, as well as the use of wire mesh over doors, windows and vents, and the removal of stagnant water from around people's homes and properties.
