Deadly Mushroom Varieties: Toxic And Fatal Fungi

While most of the thousands of mushroom species are not toxic, there are approximately 100 species that are. Some of these toxic mushrooms are deadly, and even a half mushroom of some species, such as the Amanita phalloides, or death cap, contains enough toxin to kill an adult human. The death cap is responsible for 90% of mushroom-related fatalities every year and has been implicated in the deaths of several historical figures, including the Roman Emperor Claudius. Other highly toxic species include the destroying angel, the false morel, and the webcap. Poisoning from mushrooms can occur due to misidentification of a poisonous species as edible, and symptoms can range from gastrointestinal upset to organ failure resulting in death.

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Amanita phalloides (Death Cap) is the most poisonous mushroom

While there are around 100 species of toxic mushrooms, Amanita phalloides, commonly known as the Death Cap, is considered the most poisonous of all. It is responsible for 90% of mushroom-related fatalities each year and has been involved in the majority of human deaths from mushroom poisoning.

The Death Cap is native to Europe but can now be found in other parts of the world. It resembles several edible mushroom species, including Caesar's mushroom and the straw mushroom, which increases the risk of accidental poisoning. The mushroom's toxins, amatoxins, are heat-stable and quickly damage cells throughout the body. As few as half a Death Cap mushroom contains enough toxin to kill an adult human.

The major toxic mechanism of Amanita phalloides is the inhibition of RNA polymerase II, which is a vital enzyme in the synthesis of messenger RNA (mRNA), microRNA, and small nuclear RNA (snRNA). Without mRNA, essential protein synthesis and cell metabolism are halted, leading to cell death. The liver is the principal organ affected, as it is the first organ encountered after absorption in the gastrointestinal tract, but other organs, especially the kidneys, are also affected.

Symptoms of poisoning by the Death Cap mushroom include violent abdominal pain, vomiting, and bloody diarrhea, causing rapid loss of fluids and intense thirst. These symptoms are followed by signs of severe involvement of the liver, kidneys, and central nervous system, including a decrease in urinary output and low blood sugar. Therapy for poisoning includes supportive measures, gastric decontamination, drug therapy, and, in severe cases, liver transplantation.

Toxicity varies across mushroom species

Some of the most well-known toxic mushroom species include:

• Death Cap (Amanita phalloides): Considered the most poisonous mushroom worldwide, responsible for 90% of mushroom-related fatalities each year. It bears a resemblance to wild champignons, straw mushrooms, and Caesar's mushrooms, and its toxins cause violent abdominal pain, vomiting, and bloody diarrhoea, leading to rapid fluid loss and intense thirst.
• Destroying Angels: Found in woodlands, grassy meadows, and lawns across Europe and North America, these mushrooms contain amatoxins, which are extremely toxic compounds that damage multiple organs, including the liver and heart.
• Deadly Webcap (Cortinarius rubellus): Native to northern Europe, ingestion of this mushroom often leads to fatal kidney failure, with symptoms sometimes taking up to three weeks to appear.
• False Morel: This mushroom resembles the prized and tasty morel mushroom but contains the toxin gyromitrin, which can cause neurological and gastrointestinal symptoms and even lead to death in severe cases.
• Conocybe Filaris: A common lawn mushroom in the Pacific Northwest, this species contains the same mycotoxins as the death cap and is potentially fatal, causing gastrointestinal symptoms and liver and kidney failure.

It's worth noting that mushroom poisoning often occurs due to misidentification of toxic species as edible ones. Therefore, it's crucial to only consume mushrooms purchased from reputable sources or identified as safe by a mushroom expert.

Poisonous mushrooms often resemble edible species

There are approximately 100 species of mushrooms that are toxic to humans, out of the vast number of mushroom species that exist. Many of these toxic species bear a resemblance to edible mushrooms, making them especially dangerous. The most common reason for misidentification is the close resemblance in terms of colour and general morphology of the toxic mushroom species with edible species.

For example, the death cap mushroom (Amanita phalloides) is perhaps the deadliest of all mushrooms and is found throughout Europe. It closely resembles edible straw mushrooms and Caesar's mushrooms. Its heat-stable amatoxins withstand cooking temperatures and quickly damage cells throughout the body. Within 6 to 12 hours of consumption, violent abdominal pain, vomiting, and bloody diarrhoea appear, causing a rapid loss of fluids from the tissues and intense thirst.

Destroying angel mushrooms (Amanita verna) are also incredibly toxic and similar in appearance to edible button mushrooms and meadow mushrooms. They have been collected by mistake on numerous occasions. The symptoms of ingestion take 5 to 24 hours to appear and include vomiting, delirium, convulsions, diarrhoea, liver and kidney failure, and often lead to death.

Conocybe filaris is another innocent-looking lawn mushroom that is common in the Pacific Northwest. It features the same mycotoxins as the death cap mushroom and is potentially fatal if eaten. The onset of gastrointestinal symptoms often occurs 6-24 hours after consumption, frequently leading to an initial misdiagnosis of food poisoning or the stomach flu. The patient may appear to recover, only to suffer from a life-threatening reappearance of gastrointestinal distress, coupled with liver and kidney failure.

Webcap mushrooms (Cortinarius) are very similar in appearance to each other and to several edible varieties. They feature a poison known as orellanin, which initially causes symptoms similar to the common flu. However, orellanin has an insidiously long latency period and may take 2 days to 3 weeks to cause symptoms, often leading to a misdiagnosis. The toxin ultimately causes kidney failure and death if left untreated.

Therefore, it is important for mushroom gatherers to familiarize themselves with the mushrooms they intend to collect, as well as with any similar-looking toxic species.

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Amatoxins are toxic compounds that damage many organs

Amatoxins are a subgroup of at least nine related cyclic peptide toxins found in three genera of deadly poisonous mushrooms: Amanita, Galerina, and Lepiota. Amatoxins are toxic compounds that damage many organs, primarily the liver. The liver is the principal organ affected by Amatoxins as it is the first organ encountered after absorption in the gastrointestinal tract. Amatoxins are very potent, and as little as half a mushroom cap can cause severe liver injury if swallowed.

Amatoxins are extremely toxic to humans, and Amanita phalloides and its variants make up many of the cases of fatal toxicity after consumption. Amatoxins are resistant to enzyme and acid degradation and are not destroyed by cooking or drying. They are also heat-stable and quickly damage cells throughout the body. Within 6 to 12 hours of consumption, violent abdominal pain, vomiting, and bloody diarrhea appear, causing a rapid loss of fluids from the tissues and intense thirst.

The second stage of Amatoxin poisoning occurs when the patient appears to recover transiently, and gastrointestinal symptoms resolve, but ongoing liver damage continues. This stage may last two to three days and is characterized by rising liver function transaminase, bilirubin, the development of coagulopathy, and eventually hepatic encephalopathy. In the third stage, both liver and renal function become compromised, and death can occur in three to seven days. Amatoxin-containing mushrooms are a rare but significant cause of acute fulminant liver failure. Ninety-five percent of deaths from mushroom ingestions worldwide are from amatoxin-containing mushrooms.

Treatment for Amatoxin mushroom toxicity is predominantly supportive care, with the aim of minimizing amatoxin absorption, administering activated charcoal, and maintaining hydration. There is no specific antidote, but patients must have two large-bore IVs, and fluid loss, electrolyte deficiency, and glucose should be normalized.

Mushroom poisoning symptoms vary from mild to severe

Out of the approximately 100,000 known fungi species found worldwide, only about 100 are poisonous to humans. While mushroom poisoning is rare, it can be deadly. Poisonous mushrooms contain a variety of different toxins that vary in toxicity. The severity of mushroom poisoning symptoms depends on the species, toxins, and amount ingested. Symptoms can vary from mild gastrointestinal discomfort to severe organ failure and death.

The most common consequence of mushroom poisoning is gastrointestinal upset, including vomiting, abdominal pain, and diarrhea. These symptoms typically occur within a few hours of ingestion and can be severe, requiring urgent medical care. In some cases, gastrointestinal symptoms may be delayed, occurring days or weeks after ingestion, and can lead to life-threatening complications such as liver and kidney failure.

Some mushrooms, such as the death cap (Amanita phalloides), are particularly toxic and can cause violent abdominal pain, vomiting, and bloody diarrhea within 6 to 12 hours of ingestion. This is followed by signs of severe liver, kidney, and central nervous system involvement, including decreased urinary output and low blood sugar. Death cap mushrooms are responsible for about 9 out of 10 fungi-related deaths. Other highly toxic mushrooms include Amanita bisporigera, Conocybe filaris, and Cortinarius rubellus (Deadly Webcap).

The onset of symptoms can vary depending on the type of toxin. For example, poisoning by α-amanitin may not show any symptoms for 6 to 12 hours, while poisoning by hallucinogenic mushrooms can cause euphoria, enhanced imagination, hallucinations, tachycardia, and hypertension within 15 to 30 minutes of ingestion. It's important to note that even with prompt treatment, mortality from mushroom poisoning can be high, especially if medical attention is not sought immediately.

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