Investigative update: E. coli outbreak, onions served at McDonald’s – October 30, 2024

CDC, public health and regulatory officials in several states, the U.S. Food and Drug Administration (FDA), and the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS) are collecting various types of data to investigate a multi-state outbreak to investigate. E.coli O157:H7 infections.

Epidemiological and traceback data indicate that fresh, sliced onions served at McDonald’s were the likely source of this outbreak.

Epidemiological data

As of October 30, 90 people had been infected by the outbreak E.coli O157:H7 has been reported from 13 states. Illnesses began on dates ranging from September 27, 2024 to October 16, 2024. Of the 83 people for whom information was available, 27 were hospitalized and 2 people developed hemolytic uremic syndrome, a serious condition that can cause kidney failure. One death has been reported in an older adult in Colorado. This person is not among those who have developed HUS.

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 it typically takes three to four weeks to determine whether 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 table below contains information about sick people during this outbreak (“n” is the number of people with information available for each demographic group).

State and local public health officials interview people about the foods they ate in the week before they got sick. Of the 62 people interviewed, all 62 (100%) reported eating at McDonald’s. Fifty-eight people could recall specific menu items they ate at McDonald’s. Forty-eight out of 58 people (83%) reported a menu item containing fresh, grated onions. Forty-six of 58 people (79%) reported a menu item made with quarter-pound fresh beef patties. In total, three people reported menu items that contained fresh, chopped onions, but not fresh quarter-pound beef patties. One person reported a menu item that included a quarter-pound fresh beef patty, but no fresh, sliced onions

Some people in this outbreak reported traveling to other states before their illness began. At least three people ate at McDonald’s during their trip.

Traceback information and laboratory data

The FDA has initiated inspections at a Taylor Farms processing center in Colorado and at an interesting onion grower in Washington state. The FDA cannot involve any grower at this time.

On October 22, Taylor Farms, the supplier of chopped onions to affected McDonald’s locations, initiated a yellow onion recall. Customers were contacted directly by Taylor Farms and asked to remove products. The FDA is working closely with affected companies and will continue to provide updates, including any additional recalls that may be necessary for companies that have received recalled onions.

On October 22, Colorado Department of Agriculture (CDA) laboratories analyzed subsamples of all lots of McDonald’s brand fresh and frozen beef patties collected at various McDonald’s locations in Colorado and found them to be negative for E.coli. All beef tests

FSIS has conducted a thorough investigation, including tracing beef patties served on Quarter Pounders at McDonald’s, and there is no evidence to suggest ground beef is the likely source of contamination. FSIS used specific meal information reported by sick people to trace beef patties through the supply chain to the plants where they were produced and did not identify a beef source. FSIS will continue to work closely with federal and state partners.

Public health actions

Because onions have been recalled, there is no need to avoid eating onions or other foods made with onions. Call your healthcare provider if you are experiencing severe discomfort E.coli symptoms.