Two of the four people poisoned by wild death cap mushrooms have been transferred to Sydney for medical treatment after suffering liver complications.
ACT Health confirmed the fourth person to be poisoned was receiving hospital treatment in Sydney.
ACT Chief Health Officer Paul Kelly confirmed the cases involved three women and one man - three of whom lived in the same house and ate the same meal. He would not reveal the people's ages or where they were from.
One of the patients from the weekend has also been transferred to Sydney after suffering severe liver complications.
The latest case involved a woman who ate wild mushrooms picked in the ACT.
She initially presented at Queanbeyan hospital on Monday, but ACT Health revealed the link to the mushrooms on Tuesday night.
She has since been transferred to hospital in Sydney.
‘‘Two in Sydney have had liver complications and have been transferred for further care on that basis,’’ Dr Kelly said.
A spokeswoman for NSW Health said she couldn't give an updates on the patients' condition without their consent.
Dr Kelly said the other two patients were recovering well in hospital in Canberra. Dr Kelly warned it could take as little as five grams - or a teaspoon - of death cap mushrooms to kill an adult.
‘‘It’s interesting that the three people who ate the same meal, one person is severely affected and the other two not so severely affected,’’ he said.
‘‘I’m not in position at this stage to know how much of the meal each of them ate but I would imagine the person who was severely affected possibly ate more.’’
Dr Kelly said it had been established the mushrooms eaten by the four people did not come from commercial suppliers.
He said there had been 16 cases of poisoning over the past 15 years, including the four cases this month. Of those, four were fatal. When asked about what treatment the two patients in a serious condition might require, Dr Kelly said a liver transplant ‘‘would be a desperation plan’’ but it could be a possibility.
The news comes as two of the previous death cap mushroom poisoning casualties, in hospital since Saturday, can be revealed as contract cleaners at the Australian Catholic University.
Catholic University campus dean associate professor Patrick McArdle said they were praying for their two staff members.
''We have been in touch with their employer and offered any assistance necessary to support and assist these members of our community in their current health and personal situation,'' he said.
''Our thoughts and prayers are with them at this time.''
The employer, Assetlink, was contacted for comment but did not respond by deadline.
Across the ACT, rangers have found a large numbers of death cap mushrooms. Lennox Gardens in Yarralumla and Bass Garden in Griffith were particular hot spots.
Sydney University clinical associate professor Naren Gunja said the death cap mushroom, otherwise known as amanita phalloides, was extremely poisonous and primarily attacked the liver.
He said if enough of the mushroom was consumed a person may suffer from multiple organ failure and die.
“The consumption of the mushrooms does not result in an immediate bodily reaction, although after a few hours – anywhere between six and 24 hours – a person starts to experience vomiting and diahorrea,” he said.
“The more you eat of the mushroom the more chance there is of a fatality.
“If a person swallows enough of the mushroom they may become inoperable in which case a liver transplant would not be able to save them.”
Dr Gunja said an emergency liver transplant - which a patient with sustained liver poisoning would need - was not always an easy process.
“A compatible replacement organ may not be available to the patient on short notice,” he said.
“Once consuming the mushroom, a person may also suffer secondary organ failure of the heart and the kidneys, although the primary target of the toxin is the liver.”
Dr Gunja said the death cap mushrooms can be difficult to differentiate from other mushrooms and Canberrans should refrain from picking wild mushrooms given the circumstances.
“The mushroom has a white stalk with a slight green covering on the hood with white gills forming underneath the hood,” he said.
Death caps are sometimes mistaken for straw mushrooms, commonly used in Chinese cooking.
Dr Kelly warned people not to pick wild mushrooms, saying the wrong variety could kill.
‘‘These are very toxic substances - it’s not a minor issue eating one of these mushrooms - a teaspoon can kill you,’’ he said.
‘‘There are people who do pick wild mushrooms, there is a foraging culture in the ACT and they do so at their own risk. Mature death cap mushrooms can be quite distinctive but the young ones can very easily be mistaken for other types of mushrooms. In previous episodes, we’ve had descriptions of them being very similar to edible mushrooms in other parts of the world, particularly in South East Asia and East Asia.
‘‘For that reason, our cautionary advice is don’t pick wild mushrooms, particularly in autumn in Canberra because of the risk that some of them may be the death cap variety which can kill you.’’
Dr Kelly said death cap mushrooms tended to be linked to oak trees.
‘‘We have a lot of a oak trees and that’s part of the beautiful part of living in Canberra particularly at this time of the year, but unfortunately the mushrooms are associated with oak trees. The second thing is we have quite a transient population, particularly through our internationl student population,’’ he said.
‘‘Wild mushrooms here in Canberra can be very different to what people are familiar with and they shouldn’t be picking them. They can be deadly.’’
The department has said death cap mushrooms could be found under oak trees in 13 Canberra suburbs: Acton, Ainslie, Braddon, Commonwealth Park, Deakin, Dickson, Griffith, Latham, O’Connor, Red Hill, Reid, Turner, and Yarralumla.
The ACT government has issued new warnings about the mushrooms, urging the public to be vigilant, especially if they see another member of the public picking wild mushrooms.
Signs warning of the dangers of death cap mushrooms are placed at all identified sites, including a warning in Chinese as well as the international symbol for poison.
Wild mushrooms deemed suspicious by members of the public can be reported to Canberra Connect on 13 22 81.
- with Ben Westcott and Fleta Page