According to the Food Safety Information Council, the outbreak has been linked to a farm based in Nericon, near Griffith in south-west NSW. Ten are being blamed on the consumption of contaminated rockmelon.
However, the investigation is ongoing and the rockmelons could have been purchased at any time between late a year ago and "recent days".
"Any affected product is being removed from the supply chain, so consumers can be assured rockmelons now available on shelves are not implicated in this outbreak", the NSW Food Authority said.
Two people aged in their 70s in NSW have died, and eight people from NSW, QLD and VIC have been diagnosed with Listeriosis, after consuming rockmelon between January 17 and February 9.
But for people with compromised immune system it can result in severe illness and even death.
A total of 15 people have fallen ill since eating the infected fruit, with health authorities warning people to throw away any rock melon they have at home.
Although the disease is rare, infections may cause blood poisoning and meningitis.
The melon association has urged people to discard or return any rockmelons purchased before Wednesday. The bacteria can be present in raw foods or foods may become contaminated after processing or cooking.
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The symptoms include fever, muscle aches, headache, stiff neck, confusion, loss of balance and convulsions.
Listeria is found widely in the environment, but is particularly unsafe for pregnant women and their unborn babies, and can cause death in people with compromised immune systems.
However, be aware that the incubation period for listeriosis can be up to six weeks.
People are advised to contact their doctor as soon as possible if symptoms appear.
PMA-NZ said Listeria monocytogenes has been found on rockmelons from a NSW supplier.
"Rockmelon has a rough surface and the bacteria can get in the grooves and doesn't come off easily, and spreads through the fruit during cutting", he said.
Speculating as to how rockmelon could be contaminated by high levels of listeria, CSIRO's Dr Gobius told The New Daily it would be "highly unlikely" that the listeria would have been inside the flesh of the fruit as it grows.