Investigation Details
Posted April 30, 2024
CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are collecting different types of data to investigate a multistate outbreak of E. coli O157 infections.
Epidemiologic and traceback data show that organic walnuts distributed by Gibson Farms, Inc. may be contaminated with E. coli and may be making people sick.
Epidemiologic Data
As of April 30, 2024, 12 people infected with the outbreak strain of E. coli have been reported from 2 states (see map). Illnesses started on dates ranging from February 1, 2024, to April 4, 2024 (see timeline). Of 11 people with information available, 7 (64%) have been hospitalized. Two patients have developed hemolytic uremic syndrome, a serious condition that can cause kidney failure. No deaths have been reported.
The true number of sick people in this outbreak is likely much higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because many people recover without medical care and are not tested for E. coli. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.
Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the week before they got sick. This information provides clues to help investigators identify the source of the outbreak.
The table below has information about sick people in this outbreak (“n” is the number of people with information available for each demographic).
| Demographics | Information |
|---|---|
| Age (n=12) |
Range from 6 to 84 years Median age of 57 |
| Sex (n=12) |
67% female 33% male |
| Race (n=10) |
90% White 10% African American/Black |
| Ethnicity (n=10) |
100% non-Hispanic |
State and local public health officials are interviewing people about the foods they ate in the week before they got sick. Of the 10 people interviewed, all 10 (100%) reported eating walnuts. This percentage was significantly higher than the 26% of respondents who reported eating walnuts in the FoodNet Population Survey—a survey that helps estimate how often people eat various foods linked to diarrheal illness. This difference suggests that people in this outbreak got sick from eating walnuts. Of 10 people interviewed, almost all reported buying organic walnuts from bulk bins in food co-ops or natural food stores. Investigators identified two illness subclusters of two people each who purchased bulk bin walnuts from the same store location.
Laboratory and Traceback Data
Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).
WGS showed that bacteria from sick people’s samples are closely related genetically. This suggests that people in this outbreak got sick from the same food.
Traceback data collected by FDA determined that Gibson Farms, Inc was the supplier of organic walnuts sold in bulk bins at stores where ill people shopped.
Public Health Actions
Do not eat, sell or serve recalled walnuts.
CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA), are collecting different types of data to investigate a multistate outbreak of E. coli O157:H7 infections.
Epidemiologic data show that Raw Farm brand raw cheddar cheese is making people in this outbreak sick.
Epidemiologic Data
Since the last update, one new illness and one new state were reported. One sick person in New Jersey reported eating raw cheddar cheese during travel to Colorado in the week before they got sick. As of February 28, 2024, a total of 11 people infected with the outbreak strain of E. coli have been reported from 5 states (see map). Illnesses started on dates ranging from October 18, 2023, to February 5, 2024 (see timeline). Of 11 people with information available, 5 have been hospitalized and 2 developed hemolytic uremic syndrome, a serious condition that can cause kidney failure. No deaths have been reported.
The true number of sick people in this outbreak is likely much higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because many people recover without medical care and are not tested for E. coli. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.
Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the week before they got sick. This information provides clues to help investigators identify the source of the outbreak.
The table below has information about sick people in this outbreak (“n” is the number of people with information available for each demographic).
| Demographics | Information |
|---|---|
| Age (n=11) |
Range from 2 to 75 years Median age of 25 years |
| Sex (n=11) |
36% female 64% male |
| Race (n=10) |
90% White 10% Asian |
| Ethnicity (n=10) |
100% non-Hispanic 0% Hispanic |
State and local public health officials are interviewing people about the foods they ate in the week before they got sick. Of the 9 people interviewed, 7 (78%) specifically reported eating Raw Farm brand raw cheddar cheese. This percentage was significantly higher than the 4.9% of respondents who reported eating any raw milk cheese in the FoodNet Population Survey—a survey that helps estimate how often people eat various foods linked to diarrheal illness. This difference suggests that people in this outbreak got sick from eating Raw Farm brand raw cheddar cheese.
Laboratory and Traceback Data
Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).
WGS showed that bacteria from all sick people’s samples are closely related genetically. This suggests that people in this outbreak got sick from the same food.
Officials in California, Colorado, and Utah collected various Raw Farm products for testing including raw milk, raw butter, raw cheddar cheese, and raw kefir. So far, no samples have detected E. coli. Additional testing is ongoing.
Public Health Actions
On February 26, 2024, Raw Farm brand withdrew their recall. However, CDC continues to advise people not to eat, sell, or serve Raw Farm brand raw cheddar cheese while the investigation is ongoing.
