Two people have died overnight after eating poisonous death cap mushrooms in Canberra on New Year's Eve.
A 52-year-old woman and a 38-year-old man were airlifted to Royal Prince Alfred Hospital in Sydney on Tuesday, after admitting themselves to Calvary Hospital on New Year's Day.
A third person, believed to be aged 51, drove himself to Sydney after consuming the mushrooms on Saturday and a man aged in his late 30s was discharged from Canberra Hospital yesterday.
The four people are believed to be Chinese nationals.
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Director of Emergency at Canberra Hospital, Dr Michael Hall, said today that the patient discharged yesterday was now fine, and would not have any long-term problems from the poisoning.
"We believe that he had a much smaller serve of a mushroom-prepared meal," he said.
The treatment had involved blocking the absorption of the poison from the man's stomach, and blocking the toxicity from affecting his liver.
However, he declined to give any details about the people, and said the mushrooms could have been picked anywhere in the territory.
"These patients were not specifically aware of the risks of mushrooms in the ACT region," he said.
Canberra is the one of the few places in Australia that death cap mushrooms - which were native to Europe - grow.
They are filled with amatoxin, which can attack enzymes involved in producing DNA. The poison can also trigger liver failure.
They are usually found underneath oak trees, making them more common in places like Weston Park, Yarralumla and other areas around Lake Burley Griffin.
But Dr Hall said there were concerns the mushrooms could be spreading and growing below native trees, too.
Acting ACT Chief Health Officer Dr Andrew Pengilley said the mushrooms' spores could remain underground for long periods of time, meaning they could not be eradicated.
The ACT Government had several programs to raise public awareness about the issue, including publishing information on its website and distributing material at schools, libraries, doctors and emergency departments. The information was available in a number of languages.
The Government was now looking at other ways to communicate the risks to people, particular to people who were new to the city, such as overseas students.
It also monitored areas that had large numbers of oak trees and that were therefore particularly at risk.
"It is not possible to completely map where they are. Mushrooms are quite short-lived organisms, so could be there one day and then gone," he said.
A spokeswoman for the Royal Prince Alfred Hospital said two patients had passed away overnight, while a third was still receiving treatment.
She could not confirm the age or gender of the two who had died.
A spokesman for ACT Policing said NSW Police would prepare a report for the coroner, but the matter was not the subject of a police investigation.
"The matter may be referred to us to have a look at the circumstances," he said.
"[But] until we receive a formal request, no."
The four people ate the deadly mushrooms at a New Year's Eve dinner in Canberra on Saturday night.
It is not known if the mushrooms were picked or bought before the poisoning in Canberra.
with smh.com.au and staff reporters
This reporter is on Twitter: @stephanieando