2020 Salmonella Outbreak Linked to Wood Ear Mushrooms – Updates by Date
Final Update
Updated November 4, 2020 at 3:00 PM ET
This outbreak appears to be over. People could get sick if restaurants that are unaware of the recall continue to serve recalled wood ear mushrooms because of their long shelf life. Check the U.S. Food and Drug Administration (FDA) website for the list of recalled products.
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 recalled wood ear mushrooms distributed by Wismettac Asian Foods, Inc.
This investigation is ongoing, and CDC will provide more information as it becomes available.
September 24, 2020
CDC, public health and regulatory officials in several states, and FDA are investigating a multistate outbreak of Salmonella Stanley infections.
Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting is performed on Salmonella bacteria isolated from ill people by using a standardized laboratory and data analysis method called whole genome sequencing (WGS). CDC PulseNet manages a national database of these sequences that are used to identify possible outbreaks. WGS gives investigators detailed information about the bacteria causing illness. In this investigation, WGS showed that bacteria isolated from ill people were closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.
As of September 24, 2020, a total of 41 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-two percent of ill people are female. Of 32 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 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 18 people with information, 16 (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 are conducting a traceback investigation to identify the source of the wood ear mushrooms eaten by ill people. Review of records collected to date identified that Wismettac Asian Foods, Inc., supplied wood ear mushrooms (dried fungus) to the illness cluster restaurants.
The California Department of Public Health collected dried fungus at one of the restaurants linked to an illness cluster for testing. Testing identified Salmonella in a sample of dried fungus distributed by Wismettac Asian Foods, Inc. WGS analysis is being done to determine if the Salmonella identified in the dried fungus is the same as the Salmonella from ill people.
On September 24, 2020, Wismettac Asian Foods, Inc., issued a recall of all Shirakiku imported dried fungus after the California Department of Public Health found Salmonella in the product.
Restaurants should not sell or serve recalled wood ear mushrooms distributed by Wismettac Asian Foods, Inc.
This investigation is ongoing, and CDC will provide more information as it becomes available.
