Nearly 50 illnesses, 1 death caused by E. coli outbreak linked to McDonald's Quarter Pounders

An E. coli outbreak linked to McDonald's Quarter Pounders has sickened nearly 50 people across 10 states, including one person who died of the infection.

Health officials have launched an investigation to determine which ingredient in the hamburgers was likely contaminated. In the meantime, McDonald's has stopped using the slivered onions and beef patties used for Quarter Pounders in the affected states. Diced onions and other types of beef patties have not been implicated in the outbreak, the Food and Drug Administration (FDA) has clarified. (Based on photos, the slivered onions appear to be short, Julienne-cut slices.)

E. coli, or Escherichia coli, is a bacterium often found in the guts of healthy people and warm-blooded animals. However, there are many types of E. coli, and some can make people sick. These disease-causing bacteria include E. coli O157:H7, which has been tied to the Quarter Pounder outbreak.

This type of E. coli can cause particularly severe intestinal infections, in part because it releases a toxin that can damage the lining of the intestines and thus cause bloody diarrhea. Symptoms of this infection typically arise two to five days after a person consumes contaminated food or liquid, and they can last for about five to seven days.

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Symptoms include abdominal cramps, vomiting, dehydration, fever, diarrhea with or without blood in it, fatigue and nausea. According to Johns Hopkins Medicine, roughly 8% of cases lead to hemolytic uremic syndrome (HUS), which damages blood cells and the kidneys and can lead to kidney failure and potentially death. Children and older adults face the highest risk of HUS from E. coli infections.

Forty-nine illnesses have been linked to the ongoing outbreak, including 10 hospitalizations and one death, the Centers for Disease Control and Prevention (CDC) reported Tuesday (Oct. 22). Colorado has reported the most cases, with 26, followed by Nebraska with nine. People have also gotten sick in Montana, Oregon, Wyoming, Utah, Kansas, Iowa, Missouri and Wisconsin.

"Everyone interviewed has reported eating at McDonald's before their illness started, and most specifically mentioned eating a Quarter Pounder hamburger," the CDC reported on its investigation page. (The CDC did not note how many people had been interviewed out of the total group.)

Health officials have found evidence that slivered onions used on the burgers are a likely source of the contamination, and they're also looking into the beef patties, as that's another common route of E. coli exposure.

McDonald's has stopped using Quarter Pounder slivered onions and beef patties in Colorado, Kansas, Utah and Wyoming, as well as portions of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico and Oklahoma.

"Quarter pound beef patties are only used on Quarter Pounders," the CDC has said. "Fresh slivered onions are primarily used on Quarter Pounder hamburgers and not other menu items."

People typically recover from E. coli infections without treatment but severe cases, especially those involving HUS, need treatment in a hospital. People who develop serious symptoms after eating a Quarter Pounder should seek treatment and tell their provider what they ate, the CDC advises. People who have questions about the outbreak in particular states can contact that state's health department.

This article is for informational purposes only and is not meant to offer medical advice.

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