Publisher’s Platform: What You Need to Know About E. Coli During the Walnut Outbreak

Beginning May 16, CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) will gather different types of data to investigate a multi-state outbreak E.coli O157 infections.

Epidemiological and traceback data indicate that organic walnuts produced by Gibson Farms, Inc. are distributed may be infected with E.coli and can make people sick.

Epidemiological data

As of April 30, 2024, 12 people had been infected by the outbreak 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 the eleven people for whom information was available, seven (64%) were hospitalized. Two patients have developed hemolytic uremic syndrome, a serious condition that can cause kidney failure. No deaths have been reported.

The actual number of sick people in this outbreak is likely much higher than the reported number, and the outbreak may not be limited to states with known illnesses. This is because many people recover without medical care and are not tested for it E.coli. In addition, recent illnesses may not yet be reported, as is usually the case 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 food they ate in the week before they became ill. This information provides clues to help investigators identify the source of the outbreak.

The list below contains information about sick people during this outbreak (“n” is the number of people with information available for each demographic group).

• Age (n=12): Range 6 to 84 years, median 57 years
• Gender (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 interview people about the foods they ate in the week before they got sick. Of the ten people interviewed, all ten (100%) reported eating walnuts. This percentage was significantly higher than the 26% of respondents who reported eating walnuts in the United States Population survey FoodNet– a study that helps estimate how often people eat different foods linked to diarrhea. This difference suggests that people in this outbreak became sick from eating walnuts. Of the ten people surveyed, almost all reported purchasing organic walnuts from bulk bins at food co-ops or health food stores. Researchers identified two disease subclusters of two people each who bought walnuts in bulk at the same retail location.

Laboratory and traceback data

Public health researchers use the PulseNet system to identify diseases that may be part of this outbreak. CDC PulseNet maintains a national database of DNA fingerprints of bacteria that cause foodborne illness. DNA fingerprinting is performed on bacteria using a method called Whole genome sequencing (WGS).

WGS showed that bacteria from the samples of sick people are genetically closely related. This suggests that people became sick from the same foods in this outbreak.

Traceback data collected by the FDA indicated that Gibson Farms, Inc. was the supplier of organic walnuts sold in bulk bins at stores where sick people shopped.

Public health measures

Do not eat, sell or serve recalled walnuts.

(To sign up for a free subscription to Food Safety News, click here.)