Outbreak of Salmonella Stanley Infections Linked to Wood Ear Mushrooms

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Updated October 5, 2020 at 3:15 PM ET

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA)external icon are investigating a multistate outbreak of Salmonella Stanley infections linked to wood ear mushrooms (also commonly known as kikurage or dried fungus).

Recall and Advice to Restaurants and Consumers
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At A Glance
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Do not eat, sell, or serve recalledexternal icon dried wood ear mushrooms distributed from Wismettac Asian Foods, Inc. These mushrooms were sold only to restaurants and not directly to consumers.

Consumers can ask restaurants where mushrooms are from before ordering food, such as ramen, to avoid eating recalled mushrooms. Wood ear mushrooms are also commonly referred to as kikurage, dried black fungus, dried fungus, or mu’er/mu er/mu-err.

  • Restaurant employees should check for recalled dried mushrooms and not serve or sell them. If you can’t tell where your dried mushrooms are from, throw them away.
  • Mushrooms were distributed to restaurants in six packs of five-pound bags labeled as Shirakiku brand Black Fungus (Kikurage) with Universal Product Code (UPC) bar code 00074410604305, item #60403, imported from China.
  • Clean and sanitizeexternal icon all surfaces that recalled mushrooms have come in contact with, including cutting boards, countertops, utensils, and storage bins.
  • In general, dried mushrooms should always be rehydrated using boiling water to kill any pathogens. This advice does not apply to recalled mushrooms, which should be thrown away.

Take action if you have symptoms of a Salmonella infection:

  • Talk to your healthcare provider.
  • Write down what you ate in the week before you started to get sick.
  • Assist public health investigators by answering questions about your illness.
Symptoms of Salmonella Infection
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  • Most people infected with Salmonella develop diarrhea, fever, and stomach cramps 6 hours to 6 days after being exposed to the bacteria.
  • The illness usually lasts 4 to 7 days, and most people recover without treatment.
  • In some people, the illness may be so severe that the patient needs to be hospitalized. Salmonella infection may spread from the intestines to the bloodstream and then to other places in the body.
  • Children younger than 5 years, adults 65 years and older, and people with weakened immune systems are more likely to have a severe illness.
  • For more information, see Symptoms of Salmonella Infection.
Latest Outbreak Information
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  • 43 people infected with the outbreak strain of Salmonella Stanley have been reported from 10 states.
    • 4 hospitalizations have been reported. No deaths have been reported.
  • Epidemiologic, laboratory, and traceback information show that wood ear mushrooms distributed by Wismettac Asian Foods, Inc., are the likely source of this outbreak.
    • 4 illness clusters were identified at restaurants serving ramen in three states.
    • 8 of 9 ill people linked to restaurant clusters reported eating wood ear mushrooms or ramen containing wood ear mushrooms before becoming sick.
    • Information from restaurants where ill people ate showed that wood ear mushrooms came from Wismettac Asian Foods, Inc.
  • On October 1, 2020, the California Department of Public Health identified the outbreak strain of Salmonella Stanley in recalled dried fungus samples.
  • This investigation is ongoing. CDC will provide more information as it becomes available.
Investigation Details

October 5, 2020

CDC, public health and regulatory officials in several states, and FDA are investigating a multistate outbreak of Salmonella Stanley infections.

As of October 2, 2020, a total of 43 people infected with the outbreak strain of Salmonella Stanley have been reported from 10 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from January 21, 2020, to August 26, 2020. Ill people range in age from 2 to 74 years, with a median age of 27. Sixty percent of ill people are female. Of 35 ill people with information available, 4 hospitalizations have been reported. No deaths have been reported.

Illnesses might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

Whole genome sequencing analysis of 26 bacterial isolates from ill people did not predict any antibiotic resistance. Standard antibiotic susceptibility testing by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory is underway.

Investigation of the Outbreak

Epidemiologic, laboratory, and traceback information show that wood ear mushrooms distributed by Wismettac Asian Foods, Inc., are the likely source of this outbreak.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. Of 19 people with information, 17 (89%) reported eating ramen at a restaurant in the week before their illness started. Several people reported eating at the same ramen restaurants, showing they may be part of illness clusters.

A foodborne illness cluster is defined as two or more people who do not live in the same household who report eating at the same restaurant location, attending a common event, or shopping at the same location of a grocery store in the week before becoming ill. Investigating illness clusters can provide critical clues about the source of an outbreak. If several unrelated ill people ate or shopped at the same location of a restaurant or store within several days of each other, it suggests that the contaminated food item was served or sold there.

Four illness clusters were identified at restaurants serving ramen in three states. Eight (89%) of the nine ill people linked to restaurant clusters reported eating wood ear mushrooms or ramen containing wood ear mushrooms in the week before their illness started.

FDA and states conducted a traceback investigation to identify the source of the wood ear mushrooms eaten by ill people. Traceback determined that Wismettac Asian Foods, Inc., supplied wood ear mushrooms (dried fungus) to the restaurants with illness clusters.

On October 1, 2020, CDPH identified the outbreak strain of Salmonella Stanley in recalled dried fungus samples collected at one of the restaurants linked to an illness cluster. The dried fungus was distributed by Wismettac Asian Foods, Inc.

Restaurants should not sell or serve recalledexternal icon wood ear mushrooms distributed by Wismettac Asian Foods, Inc.

This investigation is ongoing, and CDC will provide more information as it becomes available.

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