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Surge in poisonings underscores dangers of wild mushroom foraging

Amanita phalloides

California experienced a surge in wild mushrooms poisonings last December — poisonings that left three people in need of liver transplants and a toddler with permanent brain damage, according to a report published Friday by the Centers for Disease Control and Prevention (CDC).

The poisonings underscore the very real dangers of mushroom foraging, an activity that has gained popularity with chefs and foodies in recent years.

The 14 Californians in the CDC report were aged 18 months to 93 years. All became ill after eating Amanita phalloides, commonly known as the “death cap” mushroom. As background information in the report points out, the Amanita family of mushrooms is responsible for more than 90 percent of mushroom-related deaths worldwide — most likely because these mushrooms resemble several edible species.

Amanita poisonings — and deaths — have occurred here in Minnesota, too. In 2006, a 10-year-old Minnesotan girl died after eating Amanita bisporigera, commonly known as the eastern American “destroying angel.” A relative had harvested the mushroom during a visit to Phalen Regional Park in St. Paul.

Only a small amount

It does not take much amatoxin — the toxic compounds in these mushrooms — to kill a human. A lethal dose can be as low as 0.1 milligram per kilogram (2.2 pounds) of body weight, and a single mushroom can contain up to 15 milligrams of amatoxin.

Nor does cooking the mushrooms help, as amatoxin is not destroyed by heat.

Once consumed, the amatoxin is quickly absorbed into the body and soon begins to destroy cells in the liver. At first, the damage occurs silently. Symptoms — intense abdominal pain, nausea, vomiting and diarrhea — don’t typically begin until six to 12 hours after the mushroom has been consumed. Those symptoms then quickly lead to severe dehydration. 

People who are diagnosed with amatoxin poisoning are typically treated with aggressive amounts of fluids, delivered intravenously, and certain drugs.  Sometimes, however, the early symptoms of the disease are misdiagnosed as gastroenteritis, and patients are sent home, only to return a few days later with signs of liver failure.  This problem of misdiagnosis is compounded by the fact that the symptoms of mushroom poisoning often ease up for two or three days in the middle of the illness.

Early discharges are believed responsible for the relatively high fatality rate associated with amatoxin poisoning. Between 10 percent and 20 percent of cases end in death.

A massive bloom

California experienced an unusually large bloom of A. phalloides last November due to a combination of heavy rain and warm temperatures, according to the CDC report. This bloom immediately raised concern among members of a San Francisco-based mushroom club — the Bay Area Mycological Society — who alerted the California Poison Control System (CPCS). The club’s members were apparently worried that inexperienced foragers might mistake A. phalloides for benign species of mushrooms.

And that’s exactly what happened. Five days later after receiving the club’s warning, the CPCS received its first report of the season of an A. phalloides poisoning — a 37-year-old Santa Rosa man who had eaten a single death cap mushroom, which he had picked himself.

During the next two weeks, the agency received 13 more reports from four different northern California counties. Fortunately, none of the patients died, although three required liver transplants, including, tragically, an 18-month-old girl.

A poisonous family meal

The child was one of five people who became ill after eating mushrooms at the same meal. A forager — whom the child’s parents apparently didn’t know — had given the family some mushrooms he said he had picked earlier in the day in the mountains.  The child’s mother grilled them for dinner for her husband, her daughter (the 18-month-old), her sister and a friend.

During the meal, the mother ate four mushroom caps, the father ate three and the child ate half of one. The mother’s sister ate one cap and a stalk, and the friend ate various “pieces.”

They all began to get sick about nine hours later. Twenty hours after eating the mushrooms, the mother, father and child went to the emergency department of their local hospital, where they were immediately diagnosed and admitted for treatment. The parents remained in the hospital for several days, but fully recovered. The child, however, experienced liver failure and had to undergo a liver transplant. Complications from that surgery caused permanent neurologic damage.

The mother’s sister also had to have a liver transplant — partly because she was initially misdiagnosed with gastroenteritis and sent home. (She had gone to the hospital before her other family members.) When she returned to the emergency department the next day with worsening symptoms, the damage to her liver was too advanced for the organ to be saved.

The family friend sought treatment two days after eating the mushrooms. She spent six days in the hospital and had a complete recovery.

Take no chances

As the CDC report makes clear, extreme caution should be taken when foraging — or purchasing — wild mushrooms for consumption.

“Wild-picked mushrooms should be evaluated by a trained mycologist before ingestion,” the report stresses. “Inexperienced foragers should be strongly discouraged from eating any wild mushrooms.”

If you insist on eating wild mushrooms, make sure you know the symptoms of mushroom poisoning, including the fact that you may not begin to feel ill until hours after you’ve ingested the mushroom. Then be sure to get to a hospital as soon as the symptoms start. 

And take a sample of the mushroom with you.

FMI: The CDC report was published in the June 2 issue of the agency’s Morbidity and Mortality Weekly Report, where it can be read in full.

UPDATE: The Minnesota Mycological Society will help people identify any wild mushrooms they are contemplating eating. Just go to the society’s website and contact one of their officers. You will, of course, need to send a photo of the mushroom you’re querying about. “There are poisonous mushrooms in Minnesota, so caution is advised,” said the society’s president, John Lamprecht, in a phone interview with MinnPost. “Don’t eat it unless you’re 100 percent sure.” If you’re interested in foraging for wild mushrooms here in Minnesota, Lamprecht recommends you join the society, which offers a variety of educational programs.

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Comments (3)

  1. Submitted by Edward Blaise on 06/05/2017 - 10:35 am.


    As we reach the end of the Minnesota Morel mushroom season this article is nonsensical: Thousands of Minnesotans walked the woods in the last month picking an easily identifiable, seasonal mushroom that has been safely harvested for years. Find a report of a Minnesota Morel picker that misidentified and suffered consequences. And now Ms. Perry suggests that we show our harvest to a trained mycologists without telling us where to find this person or if they even exist. Giving advice that cannot be reasonably followed is of little value and to not even address Morel hunting/picking (take your choice) is unfortunate.

    • Submitted by Susan Perry on 06/05/2017 - 12:00 pm.

      A local resource


      I have updated the article with information on how you can find a trained mycologist here in Minnesota to help identify foraged mushrooms.

  2. Submitted by Curt Carlson on 06/05/2017 - 01:51 pm.

    False morels

    From Wikipedia: “The name false morel is given to several species of mushroom which bear a resemblance to the highly regarded true morels of the genus Morchella. Like Morchella, false morels are members of the Pezizales, but within that group represent several unrelated taxa scattered through the families Morchellaceae, Discinaceae, and Helvellaceae, including the genera Gyromitra and Verpa.

    The edibility of Gyromitra esculenta has been recently brought into question. Gyromitra esculenta—regarded as delicious—is known to be potentially deadly when eaten fresh, but research in the 1990s show that toxins remain even after proper treatment.

    While many people eat false morels without apparent harm, some people have developed acute toxicity and recent evidence suggests that there may be long-term health risks as well.”

    While morels are regarded as nearly impossible to misidentify, a certain amount of care and, preferably, education is advisable when eating any wild mushrooms.

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