A deadly E. coli outbreak linked to McDonald's Quarter Pounder has prompted the restaurant chain to pull the item from menus in select states.
One person has died while nearly 50 others fell ill after eating the burgers, according to the Centers for Disease Control and Prevention.
The illnesses have been reported in Colorado, Nebraska, Iowa, Kansas, Missouri, Montana, Oregon, Utah, Wisconsin and Wyoming.
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Investigators are working to determine whether fresh slivered onions, used in Quarter Pounders, are the source of the outbreak. While that investigation is ongoing, McDonald's says it has stopped using those onions in the affected states.
"The majority of menu items are not affected," Joe Erlinger, president of McDonald's USA, said. "Other beef products at McDonald's, including the cheeseburger, hamburger, Big Mac, McDouble and the double cheeseburger, are not impacted."
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“It is important to note that the onset dates for this disease are between, at this point, Sept. 27 and Oct. 11. If there has been contaminated product within our supply chain, it’s very likely worked itself through that supply chain already,” Erlinger added in an interview on NBC's "TODAY."
The CDC says some people are more at risk of E. coli infection than others. They include young children, adults 65 years and older and people with a weakened immune system.
Signs of E. coli infection include diarrhea and a fever higher than 102 degrees, vomiting and dehydration. In serious cases, kidney failure and death can occur.