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Experts warn of the dangers of eating wild mushrooms

Foraging and eating wild mushrooms can turn deadly if you're unsure how to tell the toxic varieties from the edible kind. The risks are illustrated in a case study published today in the Canadian Medical Association Journal.

"Distinguishing safe from harmful mushrooms is a challenge even for mycologists," or biologists who specialize in fungi, wrote the study authors from the Sunnybrook Health Sciences Center in Toronto wrote.

Specimens of Amanita bisporigera at varying stages of maturity collected from the fruiting patch where the patient and her husband had foraged. Reprinted with permission from the publisher, 8872147 Canada Inc., a Canadian Medical Association company

The paper focuses on the case of a previously healthy 52-year-old immigrant woman who had eaten wild mushrooms that she and her husband -- who had previous experience foraging in his native country -- found in a local park. The woman came to the emergency room with severe abdominal pain and gastrointestinal distress, including nausea and vomiting. She also brought samples of the wild mushrooms she had consumed, which turned out to be of the toxic species Aminata bisporigera.

The study authors explained that people poisoned from toxic mushrooms go through three phases of illness. The first involves gastrointestinal symptoms, including pain, nausea, vomiting and diarrhea, within six to 24 hours of ingestion. Next comes a false "recovery period" in which the patient appears to improve. The researchers point out that this phase can be dangerous, as it could result in premature discharge from the hospital or emergency room.

Finally, about 48 hours after consuming the poisonous mushrooms, the liver begins to fail, leading to multi-organ failure and possible death.

No antidote exists for mushroom toxicity, and the study authors encourage physicians to provide aggressive care to combat symptoms, monitor liver function, and look into an organ transplant in case of liver failure. Although charcoal can be used to absorb the poison, delayed development of symptoms and hospitalization limits its effectiveness because it needs to be administered as soon as possible.

The woman in the case study survived and eventually needed a liver transplant.

The researchers caution that as foraging becomes more common, people need to be aware of the risks of misidentifying mushrooms. They say there are about 6,000 reports of illness from poison mushrooms in the United States each year, but the actual number of cases is believed to be much higher. Mushrooms of the Amanita genus, which includes over 600 types, cause the most poison-related deaths.

"Foragers should be advised that poisonous mushrooms and edible mushrooms can look very similar and mushrooms of uncertain identity should not be eaten," study author Dr. Corey Stein told CBS News. "People need to be aware that wild mushrooms, despite sometimes growing in environments we consider to be safe, such as public parks, can pose extreme health risks."

The authors note that "this information is especially important for immigrants who might mistake local poisonous mushrooms for familiar edible species from their native land."

They also recommend public health authorities be informed of possible cases of poisoning so they can locate the toxic mushrooms and prevent future incidents.