Traces of the virus, which can affect both animals and humans, have been detected in mosquitoes in Queensland, New South Wales and Victoria.
A NSW Health spokesperson stated that the disease had been detected in samples from commercial pig farms at five locations in southern and western New South Wales.
The findings indicate that the virus is likely to be circulating in the mosquito population.
NSW Chief Health Officer, Dr Kerry Chant, stated that it was "really important to protect yourself from mosquito bites as mosquitoes can spread viruses including Japanese encephalitis,"
However, Victoria's Chief Health Officer Professor, Brett Sutton, states that the disease cannot be passed between humans. Asserting that people can take simple steps to prevent themselves from getting the illness from mosquitos.
"We can all protect ourselves by avoiding mosquito bites, including covering up, wearing loose-fitting clothing and using mosquito repellents," Professor Sutton said.
Occasionally, Japanese encephalitis (JEV) can cause severe neurological illness with headaches, convulsions and reduced consciousness.
"There is no specific treatment for JEV or other mosquito-borne viruses," Dr Chant said.
"The best way to avoid infection is to avoid being bitten by mosquitoes." she said.