The Japanese encephalitis virus was discovered by a second pigsty in Queensland after a human case occurred in the state last month.
Outbreaks have occurred on pig farms that have spread to at least 18 people in New Wales, South Australia and Victoria and have killed two people.
Queensland Biosafety says the virus was found in a second pigsty but did not reveal the location of the facility.
Last month, a 60-year-old woman with the virus was hospitalized in critical condition after she visited the south of the state, where the first outbreak of pig farming in Queensland was discovered.
“Japanese encephalitis has been confirmed in two piggeries in Queensland,” a spokesman for Biosecurity Queensland told AAP on Thursday.
“Queensland Biosafety works closely with the industry and provides advice on preventative measures and signs to look for.”
In Australia, 18 confirmed cases of the Japanese encephalitis virus in humans: six in New Wales, seven in Victoria, four in SA and one in Queensland.
One case in New Wales and another in Victoria were fatal.
The virus is spread by mosquitoes and can infect animals and humans. However, it cannot be transmitted from person to person or when consuming animal products.
About 99 percent of cases are asymptomatic, but some people may have a fever and headache.
One percent may experience a severe infection including seizures, paralysis, neck stiffness, tremor and coma.
Children under the age of five and the elderly are more prone to developing a severe infection.
The virus, which has no specific treatment, can cause severe neurological diseases, in some cases with headaches, seizures and decreased consciousness.
Authorities say the best protection against the virus is to take steps to avoid mosquito bites.
The discovery of the virus outside the far north of Australia has alarmed experts. The last confirmed local cases of human disease were recorded in the region in 1998.
On Friday, the federal government announced a $ 69 million plan to fight the spread of the disease, including the purchase of another 130,000 doses of the vaccine.
A $ 5 million information and publicity campaign will be launched, and $ 3.5 million will help conduct human trials.
To understand the spread, the government will strengthen surveillance of mosquitoes and animals, model the potential spread of the virus and carry out mosquito control.