ACT Health has confirmed another case of death cap mushroom poisoning, bringing the total to four in less than a week.
The government was unable to provide any information about the patient and their condition was unknown.
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.
The ACT's Chief Health Officer, Doctor Paul Kelly, said they became ill after harvesting wild mushrooms in the ACT.
ACU 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.''
Three people were taken to Queanbeyan Hospital on Saturday and later transferred to the Canberra Hospital after they were poisoned by the potentially deadly fungi. Two patients were male and female with the third person's gender unknown. All three lived in the same household.
The female patient was in the most serious condition and was transferred to Royal Prince Alfred hospital in Sydney. A spokeswoman for NSW Health said they couldn't give an update on her condition as they did not have her consent.
Mr Kelly said it was concerning the poison had entered the liver of the latest female patient.
Two of the original Canberra patients are believed to be recovering well and are expected to be discharged soon.
Their employer, Assetlink, was contacted for comment but did not respond by deadline.
Across the ACT, large numbers of death cap mushrooms have been found by rangers.
Lennox Gardens in Yarralumla and Bass Garden in Griffith were particular hot spots.
The poisoning has prompted the ACT government to issue new warnings about the mushrooms, urging the public to be vigilant, especially if they see another member of the public picking wild mushrooms.
Rangers from TAMS do weekly monitoring of known locations in Canberra's urban open spaces during the death cap mushroom growing season, collecting and destroying any death cap mushrooms they find.
During this season, large numbers have been found in Lennox Gardens and Bass Garden, but on Tuesday, pest and weed officer Tristan Adrian was collecting them from a suburban park in Holt as part of his regular patrol.
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.
The additional warnings came after two people died from death cap poisoning in 2012 when a chef mistook the death cap mushrooms for straw mushrooms, commonly used in Chinese cooking, and added them to a stir-fry.
Since Saturday, Canberra Connect has taken at least six calls reporting death cap mushrooms, which are particularly prevalent under oak trees.
A TAMS spokeswoman said death cap mushrooms had a cup-like volva at the base of the stem and could be distinguished by their white gills.
Wild mushrooms deemed suspicious by members of the public can be reported to Canberra Connect on 13 22 81.