Food Poisoning Outbreak Linked to Morel Mushrooms
A recent food poisoning outbreak that resulted in the deaths of two individuals and affected 51 others has shed light on the limited knowledge surrounding morel mushrooms and the potential risks associated with their preparation.
In response to the severe illness outbreak that was traced back to Dave's Sushi in Bozeman, Montana, the U.S. Food and Drug Administration (FDA) conducted an investigation into morel mushrooms. The findings of the investigation indicated that the likely cause of the outbreak was the consumption of undercooked or raw morels. As a result, the FDA has released its first set of guidelines on how to properly prepare morel mushrooms.
According to the FDA guidance, "The toxins in morel mushrooms that may cause illness are not fully understood; however, using proper preparation procedures, such as cooking, can help to reduce toxin levels."
Despite following cooking steps, the FDA warns that there is still a potential risk of illness associated with the consumption of morel mushrooms. The agency states, "Properly preparing and cooking morel mushrooms can reduce the risk of illness, however, there is no guarantee of safety even if cooking steps are taken prior to consumption."
Jon Ebelt, spokesperson for Montana's health department, revealed that there is limited public health information and medical literature available on morel mushrooms. Additionally, samples of the morels taken from Dave's Sushi did not detect any specific toxins, pathogens, pesticides, or organic compounds.
Aaron Parker, the owner of Dave's Sushi, shared his insights on morels, describing them as a "boutique item." During their season in spring and fall, Parker purchases morels for $40 per pound. However, when bought out of season, the price can go up to $80 per pound. To preserve the sought-after earthy flavor, many recipe books recommend sautéing morels. At Dave's, Parker revealed that they use a marinade, sometimes boiling it, before serving the raw mushrooms. After conducting his own investigation, Parker discovered that boiling them for 10 to 30 minutes is the safest way to prepare morel mushrooms. Surprisingly, Parker found that many chefs across the country were unaware of the inherent risk factor and toxicity of morels, regardless of preparation.
According to the FDA's Food Code, a large majority of the over 5,000 fleshy mushroom species found in North America have not undergone toxicity testing. Out of the species that have been tested, 15 are deadly, 60 are toxic whether raw or cooked (including "false" morels that resemble edible morels), and at least 40 are poisonous when consumed raw but safer when cooked.
The North American Mycological Association provides further information on mushrooms and their toxicity.
Mushroom Poisoning in Montana
Mushroom-caused food poisonings in restaurant settings are rare — the Montana outbreak is believed to be one of the first in the U.S. related to morels — but they have happened infrequently abroad. In 2019, a morel food poisoning outbreak at a Michelin-star-rated restaurant in Spain sickened about 30 customers. One woman who ate the morels died, but her death was determined to be from natural causes. Raw morels were served on a pasta salad in Vancouver, British Columbia, in 2019 and poisoned 77 consumers, though none died.
According to Marian Maxwell, the outreach chairperson for the Puget Sound Mycological Society, cooking breaks down the chitin in mushrooms, the same compound found in the exoskeletons of shellfish, and helps destroy toxins. Maxwell mentioned that morels may naturally contain a type of hydrazine, a chemical often used in pesticides or rocket fuel, which can cause cancer. Cooking does boil off the hydrazine, but some people still have reactions even though it's cooked and most of that hydrazine is gone.
Heather Hallen-Adams, chair of the toxicology committee of the North American Mycological Association, stated that hydrazine has been shown to exist in false morels, but it's not as "clear-cut" in true morels, which were the mushrooms used at Dave's Sushi.
Before the new guidelines were issued, the FDA's Food Code guidance to states was only that serving wild mushrooms must be approved by a "regulatory authority."
Sources: Food Safety News, Environmental Protection Agency, Food and Drug Administration
The FDA's Food Code prohibits the sale of wild-picked mushrooms in restaurants or other food establishments unless they have been approved to do so. However, cultivated wild mushrooms can be sold if the cultivation operations are overseen by a regulatory agency. This was the case with the morels at Dave's Sushi. State regulations vary, as stated in a 2021 study by the Georgia Department of Public Health, which is included in the Association of Food and Drug Officials' regulatory guidelines. According to the study, Montana and several other states allow restaurants to sell wild mushrooms if they come from a licensed seller. Additionally, seventeen other states permit the sale of wild mushrooms that have been identified by a state-credentialed expert.
The study highlights the various resources that states utilize to identify safe wild mushrooms, including mycological associations, academics, and the food service industry. This suggests a need for better communication.
The study recognizes a "guidance document" as the "single most important step forward" due to the diversity in regulations and the demand for wild mushrooms.
Hallen-Adams, an expert in mushroom identification who trains people in Nebraska, points out that while "mushroom people" are aware that raw morels are poisonous, this knowledge is not common among chefs.
In the case of Dave's Sushi, Hallen-Adams believes that safety information did not reach the individuals who needed it. She suggests that labeling could address this issue.
There has not been sufficient emphasis on ensuring that consumers are aware of how to properly prepare mushrooms, according to Hallen-Adams. She believes that this is something that needs to change.
Hallen-Adams reveals that the North American Mycological Association plans to update its website to include more prominent information about the importance of cooking mushrooms, specifically mentioning morels.
Montana's health department intends to publish guidelines on morel safety in the spring, ahead of morel season.
KFF Health News, formerly known as Kaiser Health News (KHN), is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF — the independent source for health policy research, polling, and journalism.
