A 60-year-old Victorian man has died from a mosquito-borne virus that hasn't been detected in humans in more than 20 years.
The state's Department of Health said it is investigating how he contracted the virus after an autopsy revealed the cause of death was the Japanese Encephalitis Virus (JEV).
The man died on February 28 and is the first person ever to die from the rare virus in Victoria.
Last detected in humans in Australia in 1995, JEV is a viral disease that occurs mostly in pigs and horses but can be spread to humans by bites from mosquitoes carrying the disease.
The virus can't be transmitted between humans or by eating pork and other animal products.
Australia's federal Department of Health has declared the unfolding situation as a Communicable Disease Incident of National Significance, meaning it is taking action to educate the community about JEV and what precautions to take, including a vaccine rollout.
"A national approach is required in relation to the coordination of health policy, interventions and public messaging," Acting Chief Medical Officer Sonya Bennett said in a statement.
"We strongly advise people take steps to limit their exposure to mosquitoes and avoid mosquito habitats such as stagnant water."
Dr Bennett said experts are working to support the response, which includes mosquito surveillance and control measures, identification of those at risk, public health communicaition and a rollout of vaccines.
However, health experts say severe illness from the disease is rare and in most cases, people will experience no symptoms.
"A very small proportion of people infected may develop a serious illness such as encephalitis and experience symptoms including neck stiffness, severe headache and coma, and more rarely, permanent neurological complications or death," Dr Bennett said in a statement.
On Thursday, officials confirmed a case of JEV in Queensland that was being treated in a Brisbane hospital. The Department of Health said they are aware of other cases in multiple states.
This comes as JEV was detected in piggeries across the country and on March 1 urged pig and horse owners to report any symptoms of the virus.
"The most common symptoms in pigs are mummified or stillborn piglets, or piglets who show neurological problems in the first six months of life. The disease tends to be asymptomatic in adult sows, but boars can experience infertility and testicle congestion," Chief Veterinary Officer Mark Schipp said.
"Horses can experience a range of symptoms. While most infected horses do not show signs of disease, some more severe signs of JEV in horses include fever, jaundice, lethargy, anorexia and neurological signs which can vary in severity."
Last week, the Ministry of Health confirmed no cases of JEV have been detected in New Zealand.
