As summer fades and the days become wetter and cooler, you may begin to notice wild mushrooms infiltrating your backyards and local green spaces. Autumn provides ideal growing conditions for a number of species, including Amanita phalloides – otherwise known as the death cap mushroom.
Death cap mushrooms are responsible for 90% of mushroom-related deaths around the globe, making it the world’s most poisonous mushroom. In Australia, death cap mushrooms are usually only found in Victoria and the Australian Capital Territory (ACT), often growing underneath oak trees.
Thoughts of beef wellington aside, mushroom poisonings are generally the result of mistaken identity. In the early stages of growth, death cap mushrooms can resemble other edible varieties, such as field and straw mushrooms. According to accounts from unsuspecting foragers, death cap mushrooms actually taste quite pleasant.
Death cap mushrooms contain three main types of toxins: amatoxins, phallotoxins and virotoxins. The deadliest of these is an amatoxin called α-amanitin, or AMA for short. AMA toxin attacks the liver and kidneys, stopping these organs from carrying out essential cellular functions, such as making new proteins. As many true crime enthusiasts may be aware, AMA toxin can’t be destroyed by cooking or dehydrating.
Initially, the cell damage caused by AMA toxin leads to nausea, diarrhoea and other gastrointestinal symptoms. This starts from about six to 12 hours after eating a death cap mushroom. Over the following week and beyond, symptoms can progress to liver and kidney failure. Some people recover fully with intravenous fluids and decontamination with activated charcoal. Others may need a liver transplant or they may develop internal bleeding, which can be fatal.
In terms of medication, people admitted to hospital with death cap mushroom poisoning may be given a combination of medications, including silibinin, acetylcysteine and penicillin. However, it’s unclear how these medications work against the AMA toxin, and outcomes are mixed. Unfortunately, there is no specific antidote to reverse the effects of death cap mushroom poisoning – well, not yet at least.
In May 2023, a team of researchers from Australia and China surprised the scientific community by reporting on a compound that appears to block the toxic effects of AMA toxin. This compound, called indocyanine green (ICG), is a widely available iodide-based dye that has been used in medical imaging of the eye since 1956.
The researchers published a study in Nature showing that in mice treated with AMA toxin, ICG reduces liver and kidney damage, and improves the overall likelihood of survival. While this research is yet to be tested in humans, at the very least it has helped researchers to better understand death cap mushroom poisoning at a cellular level.
Until such time that science can deliver an effective antidote, it’s probably best to steer clear altogether. In short, avoid picking and eating any kind of wild mushroom. And certainly, don’t cook them for family and friends at a dinner party.
