The Japanese encephalitis outbreak has now spread to humans.
A Queenslander is the first confirmed case.
This mosquito-borne disease has also today been confirmed as the source of pig deaths on three farms in the north of Victoria.
Several farm workers in Victoria are also believed to have been infected and are also in hospital being treated.
Only yesterday the virus was found to have infected the person in Queensland.
The confirmed case had recently travelled in regional southern Queensland and is currently being treated in a Brisbane hospital.
The human case follows a detection at a piggery in southern Queensland last week.
There have also been detections in NSW, South Australia and Victoria.
The Japanese encephalitis virus has now been confirmed as the cause of death of piglets at three separate pig farms in Victoria's north.
One in the Loddon Shire, one in the Campaspe Shire and one in the Wangaratta Shire.
The disease was previously unknown in Australia.
A public health alert has been issued in flood-hit Queensland.
The virus is spread through the bite of an infected mosquito to people and animals.
In animals, it mostly occurs in pigs and horses.
Clinicians at Queensland hospitals have been asked to be alert to the possibility of JEV in people presenting with encephalitis or a similar illness.
Most human infections of JEV cause no symptoms or mild symptoms such as headache or fever.
A person with severe disease may present with inflammation of the brain (encephalitis), characterised by sudden onset of vomiting, high fever and chills, severe headache, sensitivity to light, neck stiffness and nausea/vomiting.
Children aged under five years of age and older people who are infected with JEV are at a higher risk of developing more severe illness.
There is no risk to humans from consuming pork or pig products. Pork products are safe to eat.
The virus cannot be spread directly from person to person.
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Agriculture Victoria has established an incident management team with staff on the ground to conduct surveillance activities and to provide information and advice to farmers.
Victoria's chief veterinary officer Dr Graeme Cooke said since the announcement of the first positive Japanese encephalitis detection last weekend, a number of Victorian farmers had made contact with Agriculture Victoria and submitted samples for testing.
"Japanese encephalitis virus causes reproductive failure in pigs, primarily through stillbirths and piglets that may show signs of central nervous system disease," Dr Cooke said.
"Japanese encephalitis can be transmitted to humans through infected mosquitoes and in rare cases can cause encephalitis - a central nervous system disease which can be life threatening so we are working closely with the Department of Health to understand the implications and to communicate to farmers how they can reduce the risk of human exposure."
Agriculture Victoria is also encouraging horse owners to take steps to protect their horses as they are also susceptible to Japanese encephalitis if bitten by infected mosquitoes.
In horses, symptoms include lethargy, nervous signs or sometimes hyperexcitability. To date there have been no confirmed cases of Japanese encephalitis in horses in Australia.
Dr Cooke encouraged animal owners to report any cases of unexplained pig deaths, especially piglets, or unexplained horse illnesses, to the 24-hour Emergency Animal Disease Watch Hotline on 1800 675 888, to your local vet or to Agriculture Victoria animal health staff.
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