Collaboration with CDC and USDA points to slivered onions as the likely source.

The FDA is collaborating closely with the CDC, USDA FSIS, state health authorities, and several companies as they continue investigating a recent outbreak of E. coli O157 infections linked to slivered onions served at select McDonald’s locations. Data from both epidemiologic assessments and traceback analyses suggest that these onions, distributed to various McDonald’s outlets, are the most likely source of the infections.

The outbreak, which has now spread to 13 states, has affected 90 people as of October 30.

Individuals reported the onset of symptoms between September 27 and October 16, 2024. Out of the 83 people with available information, 27 have required hospitalization, with two patients developing hemolytic uremic syndrome (HUS), a severe condition associated with kidney failure.

Tragically, one fatality has been recorded, involving an older adult from Colorado, who was not one of the HUS patients.

Further reports of illnesses have emerged but predate the actions taken by McDonald’s and their supplier, Taylor Farms, to withdraw slivered onions from the affected food service locations.

Interviews with 62 affected individuals revealed that all had recently dined at McDonald’s, with 100% confirming restaurant visits before experiencing symptoms.

Furthermore, 83% of those interviewed confirmed they had consumed a menu item containing fresh slivered onions, while 79% reported consuming a Quarter Pounder made with fresh beef patties.

Although some reported only having onions or the Quarter Pounder, the data emphasizes a strong association between the consumption of slivered onions and the reported cases of E. coli.

FSIS, which has been conducting an independent investigation, focused extensively on the ground beef patties served in McDonald’s Quarter Pounders but found no indication of contamination linked to the beef supply chain.

This investigation involved a detailed analysis of meal records reported by ill individuals and traced beef products back through the supply chain to the processing facility.

The Colorado Department of Agriculture also conducted tests on beef patty samples, all of which tested negative for E. coli O157. FSIS continues its collaboration with federal and state health officials to further address concerns surrounding the outbreak.

Taylor Farms, the primary supplier of onions to the affected McDonald’s locations, initiated a recall of yellow onions on October 22, 2024.

These onions had been distributed to McDonald’s and other food service clients, prompting the FDA to work alongside Taylor Farms and direct customers to evaluate the need for additional recalls.

However, it appears unlikely that the recalled onions reached grocery stores or were sold directly to consumers. Taylor Farms has informed all food service clients who received the onions to halt their use and ensure that any remaining recalled onions, including those potentially frozen, are properly disposed of.

Meanwhile, the FDA has commenced inspections at a Taylor Farms processing center in Colorado and is evaluating an onion grower of interest-based in Washington state. The FDA’s ongoing investigation aims to trace any further links in the supply chain that may have contributed to the outbreak, ensuring comprehensive oversight of this issue.

According to McDonald’s statements, slivered onions are no longer being served in the affected states, significantly reducing the current risk of illness. The FDA has indicated that, given the recall of these onions, the risk to public health is now low as contaminated onions are no longer accessible in food service locations.

Case Count Map Provided by CDC

Case Count

• Total Illnesses: 90
• Hospitalizations: 27
• Deaths: 1
• Last Illness Onset: October 16, 2024
• States with Cases: CO, IA, KS, MI, MO, MT, NE, NM, OR, UT, WA, WI, and WY
• Recalled Onion Distribution*: CO, IA, ID, KS, MO, MT, NE,  NM, NV, OK, UT, and WY

*Distribution has been confirmed for the states listed, but the product could have been distributed further, reaching additional states.