McDonald’s Quarter Pounder has been linked to an E. coli outbreak that has left at least 49 individuals severely affected. On October 23, Taylor Farms, the supplier of the burger’s raw onion ingredient, announced a recall of four types of raw onion products, according to Reuters.

The FDA identified the contaminated source as the raw onions used in the burgers and has pinpointed the supplier’s farm. McDonald’s confirmed on October 24 that the onions for their hamburgers come from Taylor Farms, which has initiated the recall.

Restaurants using these four types of raw onions have been instructed to stop using them and dispose of their inventory. As a precaution, McDonald’s has temporarily removed this menu item from its offerings.

An FDA spokesperson stated that they are investigating Taylor Farms, as well as all potential sources of contamination.

As of October 23, at least 49 people across the United States are suspected of eating the contaminated hamburgers and contracting E. coli. Notably, an elderly adult in Colorado has died, and 10 others, including a child who developed hemolytic uremic syndrome, have been hospitalized.

In response to the recall, several chain restaurants such as Taco Bell and Illegal Pete’s in Colorado have halted the use of raw onions. Yum! Brands, the parent company of Taco Bell, also indicated that some Pizza Hut and KFC locations are no longer using raw onions, although these chains have not reported any food poisoning cases.

Taylor Farms, based in California, specializes in providing fresh-cut fruits and vegetables to foodservice operators.

The specific strain of E. coli identified in this outbreak, O157:H7, is particularly harmful and can damage the intestinal wall.

Shortly after the recall was announced, McDonald’s faced legal action. Ron Simon & Associates, a law firm specializing in food safety lawsuits, reported on October 24 that they filed a second lawsuit related to the hamburger contamination. The plaintiff, Clarissa DeBock, a Nebraska resident, claims she purchased a Quarter Pounder on September 18, fell ill days later, and required hospitalization, where she was confirmed to have been infected with the O157:H7 strain.

Another plaintiff, Eric Stelly from Colorado, reported suffering severe gastrointestinal symptoms after eating a McDonald’s hamburger, expressing his distress over the situation.