McDonald’s has identified the cause of the E. coli outbreak in multiple states – and it’s not the burger patties

The Quarter Pounder is back on the McDonald’s menu.

Last week, America’s most popular fast-food chain was the target of a food safety alert from the Centers for Disease Control and Prevention that said Quarter Pounders may be responsible for an E. coli outbreak in several states. As Food & Wine previously reported, nearly 50 illnesses in 10 states have been reported to the organization, including 10 hospitalizations and one death related to the outbreak. As of Oct. 24, that number rose to 75 illnesses in 13 states, with two customers developing “hemolytic uremic syndrome, a serious condition that can lead to kidney failure,” according to the Food and Drug Administration (FDA).

However, as of Sunday, the chain reintroduced the burgers to its nearly 900 restaurants affected by the outbreak, representing about 20% of all McDonald’s restaurants in the United States. However, they are served with one missing menu item: onions.

“The issue appears to be isolated to a specific ingredient and region, and we remain highly confident that all contaminated products related to this outbreak have been removed from our supply chain and are no longer available at all McDonald’s restaurants,” Cesar Piña said , head of SVP, McDonald’s supply chain officer for North America said this in a statement published on the company’s website.

According to the statement, the 900 restaurants involved “had received sliced ​​onions from Taylor Farms’ Colorado Springs facility in the past,” which is currently being investigated by the FDA as a possible cause of the outbreak.

“The FDA is continuing its investigation into the Taylor Farms facility in Colorado Springs,” Piña said. “As a reminder, on October 22, McDonald’s removed sliced ​​onions from this facility from our supply chain and announced that we have decided to cease sourcing onions from the Taylor Farms facility in Colorado Springs indefinitely. In the last few days, you have probably seen that additional food service providers and restaurant brands that received onions from this facility have stopped selling onions and/or stopped recalling onions.”

This menu change affects McDonald’s locations in Colorado, Kansas and Wyoming, as well as some locations in Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma and Utah. Piña added in the statement that Colorado Department of Agriculture testing did not detect E. coli in samples of Quarter Pounder beef patties and that no further testing is planned for that ingredient.

The FDA also noted that symptoms of E. coli “begin several days after consuming contaminated food or up to nine days later” and include everything from “severe stomach cramps, diarrhea, fever, nausea and/or vomiting.” It states that “some infections can cause severe bloody diarrhea and lead to life-threatening illnesses.” If you think you are infected, contact your doctor immediately.