WEDNESDAY, Dec. 4, 2024 (HealthDay News) — An investigation into an E. coli outbreak linked to McDonald’s Quarter Pounders has officially been closed, the U.S. Food and Drug Administration announced Tuesday.

In total, 104 people from 14 states were sickened and 34 were hospitalized during the outbreak, while one older person in Colorado died, the FDA said in its health update. The likely source of contamination was determined to be raw, slivered onions that were put on the signature burgers, the agency added.

However, there is no “continued food safety concern” because the affected onions were recalled and there haven’t been any new illnesses reported since McDonald’s removed the onions from its menu on Oct. 22, health officials said.

While the evidence on what triggered the outbreak was slim, one sample from now-recalled onions supplied by Taylor Farms, a Colorado-based vegetable and fruit grower, and an environmental sample from an onion grower in Washington State tested positive for E. coli. However, those samples did not match the strain found in those who fell ill, the FDA noted.

Still, investigators said they determined the yellow onions were the likely culprit based on interviews with those who were sickened and from information provided by the distributors of the product. Of the people who recalled what they ate, roughly 84 percent had a menu item with slivered onions, the agency said.

McDonald’s has since said it would stop using Taylor Farms onions from its Colorado Springs facility.

“The process to reach this point has at times felt long, challenging and uncertain,” Michael Gonda, McDonald’s North America chief impact officer, and Cesar Piña, the company’s chief supply chain officer, said in a statement issued Tuesday. “But it is critical that public officials examine every possible angle, and we are deeply grateful that they moved quickly to identify and, in partnership with McDonald’s, contain the issue.”

The company said recently that it has resumed selling Quarter Pounders with slivered onions from different sources at affected locations.

“McDonald’s identified an alternate supplier for the approximately 900 restaurants that had temporarily stopped serving Quarter Pounder burgers with slivered onions,” the company said in a Nov. 14 statement. “Over the past week, these restaurants resumed the sale of Quarter Pounder burgers with slivered onions.”

In its statement, McDonald’s added that “food safety is something we will never compromise on, and we remain committed to doing the right thing.”

Still, several lawsuits have been filed against McDonald’s since the outbreak was first announced, including a proposed class action lawsuit, NBC News reported.

Most people infected with the E. coli strain recover without treatment. Milder symptoms often include stomach cramps, bloody diarrhea and vomiting. In more severe cases, people can develop high blood pressure, kidney disease, neurological problems or hemolytic uremic syndrome — a condition that can trigger kidney failure, according to the CDC.

More information

The CDC has more on E. coli.

SOURCES: U.S. Food and Drug Administration, health update, Dec. 4 and Nov. 13, 2024; McDonald’s statement, Dec. 4 and Nov. 13, 2024; NBC News

Copyright © 2024 HealthDay. All rights reserved.