South Australian authorities are urging travellers to take precautions this Easter after the detection of mosquito-borne viruses outside the usual areas.
SA Health director of health protection Michaela Hobby said the state's surveillance program was expanded after the emergence of Japanese encephalitis virus (JEV).
"This year we are seeing widespread mosquito virus activity well outside areas where we would normally expect to see it," she said.
"We've seen Murray Valley encephalitis virus being picked up in sentinel chickens and mosquito traps at Clare.
"We've seen Barmera Forest virus and Ross River virus at Elliston, and we've also picked up Ross River virus in the Barossa Valley area."
She said people travelling this Easter should not assume they are immune to mosquito-borne diseases, even if they have received a JEV vaccine.
"Our message is clear — wherever you are this Easter, this autumn, be aware that summer's over but the risk of mosquito-borne disease isn't," Ms Hobby said.
"Whether you're staying home having a barbecue, heading to the coast or the river or travelling interstate, there's lots of mosquito activity across the country."
How to protect yourself
There is no vaccine for Murray Valley encephalitis or the Ross River or Barmera Forest viruses.
Ms Hobby said people should check tents and caravans for holes.
She also urged the public to wear closed shoes, loose-fitting clothing and apply insect repellent.
"Make sure you're protecting yourself from top to toe and you're getting that repellent on like you would with sunscreen," Ms Hobby said.
Repellent should contain DEET, picaridin or lemon eucalyptus.
SA Health advised people to limit being outdoors between dusk and dawn.
"No matter where you live in South Australia, if you get bitten by a mosquito, you could be at risk of serious or potentially fatal disease," Ms Hobby said.
"Your best protection is prevention."