E. coli outbreak in Quarter Pounders traced to onions

On October 22, 2024, the Centers for Disease Control & Prevention announced a multi-agency investigation into a “severe” E. coli outbreak linked to McDonald’s Quarter Pounder.  A company statement indicates the burger’s signature slivered onions may be the source of an outbreak already spanning 10 states with dozens of reported illnesses and one death. Here’s what you should know. 

Consumers may find that the Quarter Pounder is not currently available at McDonald’s restaurants in some locations as a “fast-moving” investigation points to the burger—or at least one of its components—as the source of a deadly E. coli outbreak that has sickened 49, hospitalized 10, and caused one death across 10 states.

The CDC, alongside public health and regulatory officials in several states, the FDA, and the USDA’s Food Safety and Inspection Service (FSIS) are collecting different types of data about the outbreak. This article will be updated as new data are released. 
 

Multistate outbreak: Where people are getting sick

At the time of publication, the CDC reported 49 illnesses, though the agency notes that that figure is “likely much higher;” the reports span 10 states. Of those 49, 10 have been hospitalized, one has died, and one other has contracted a serious condition called hemolytic uremic syndrome, which can cause kidney failure.

The reported illnesses began between Sep. 27, 2024, and Oct. 11, 2024. Early data from the investigation show that onions—specifically the burger’s trademark “fresh slivered onions”—are a likely source of contamination. The agencies are still working to determine if the onions were served or sold at other businesses. As a precaution, McDonald’s has removed the Quarter Pounder from the menu at some locations.

Known cases of E. coli linked to McDonald’s Quarter Pounder are in Colorado (26)—including the older patient who died and the case of HUS—as well as Nebraska (9), Wyoming (4), Utah (4), Iowa (1), Kansas (1), Missouri (1), Montana (1), Oregon (1), and Wisconsin (1). 

The CDC warns that the outbreak “may not be limited to the states with known illnesses,” as many people who contract E. coli recover without medical care, and some cases may not have been reported. 

What to do if you’ve had a Quarter Pounder recently

The CDC and McDonald’s report that McDonald’s has stopped using fresh slivered onions and quarter-pound beef patties in several states to protect their customers while a source of illness is confirmed. However, the full scope of the outbreak is not yet apparent, so consumers who have recently had a Quarter Pounder in any state should watch for signs of illness. 

Call your healthcare provider if you’ve had a McDonald’s Quarter Pounder hamburger and have severe E. coli symptoms, including:

• A fever higher than 102°F, especially if you also have:
  • Diarrhea for more than 3 days that is not improving
  • Bloody diarrhea
• Vomiting that prevents you from drinking adequate fluids
• Signs of dehydration, including:
  • Not peeing much
  • Dry mouth and throat
  • Feeling dizzy when standing up

Symptoms of E. coli infection

E. coli O157:H7, the strain responsible for this outbreak and most others, is the most common strain to cause illness in people. Anyone can get infected with E. coli, but some groups are more likely to experience severe symptoms: those older than 65 or younger than 5, people with weakened immune systems, and people who travel internationally. 

Symptoms range from none to severe and begin to appear 2 to 4 days after eating or drinking contaminated foods or water. Most people with E. coli infection have diarrhea (which may be bloody or watery), stomach cramps, vomiting, and low-grade fever, and usually recover within 5 to 7 days without medical care.

Learn more at Nutrition Action: What you need to know about food poisoning

When to seek treatment for suspected E. coli infection

If you have symptoms of E. coli infection, the CDC recommends drinking plenty of fluids, resting as much as possible, and washing your hands thoroughly and often. Many people recover at home and without any medical attention. 

There are some rules to treatment for E. coli, though: Treating E. coli O157:H7 with antibiotics—or with antidiarrheal drugs like Imodium or Pepto-Bismol—can make you sicker. Call your healthcare provider before taking any over-the-counter drugs to treat suspected E. coli infection, especially if you have a high fever or bloody diarrhea.

If you have any of the following symptoms, seek medical attention immediately:

• Diarrhea or vomiting that lasts more than two days
• Bloody diarrhea or urine
• A fever higher than 102°F
• Dehydration (little to no urination, very dark urine, extreme thirst, dry mouth, dizziness, or extreme fatigue)

Children have an increased risk of serious illness

Children, particularly those under age 5, can experience more severe symptoms from Shiga toxin-producing E. coli (STEC) infection. Dehydration is especially dangerous for young children. Give children extra fluids and oral electrolyte solutions, like Pedialyte, at the first sign of illness; do not wait for signs of dehydration.

Do not give children under age 12 Pepto-Bismol, Kaopectate, or similar antidiarrheal products. Seek medical attention immediately if your child has the following symptoms:

• Diarrhea or vomiting that lasts more than two days
• Symptoms of STEC infection, especially bloody diarrhea or urine
• A fever higher than 102°F
• Dehydration (little to no urination, very dark urine, extreme thirst, dry mouth, dizziness, or extreme fatigue)

Hemolytic uremic syndrome: What to watch out for

Shiga toxin-producing E. coli (STEC) causes bleeding in the digestive tract and increases risk of hemolytic uremic syndrome; severe cases may cause HUS, which can lead to kidney failure and even death. Symptoms of HUS include:

• Urinating less often or not at all
• Loss of color in cheeks and lower eyelids
• Unexplained bruising or petechiae (tiny red spots on the skin)
• Extreme irritability or fatigue
• Loss of alertness or awareness

HUS is a medical emergency. People with symptoms of HUS should be hospitalized immediately to prevent kidney failure and other serious complications. If you have any symptoms of HUS, go to the nearest emergency room immediately.

Prevention is key to reducing the spread of foodborne illness

Anyone can be infected with E. coli, which typically contaminates food through contaminated water, animal waste, or through people who have E. coli. 

The first and best barrier to spreading E. coli is handwashing. Even if you contract E. coli infection through food, you can spread your infection to others through unwashed hands, especially if you touch others directly, prepare food, and touch household surfaces.

• Use warm or cold water
• Lather your hands thoroughly with soap 
• Scrub for at least 20 seconds, including the backs of your hands, under your nails, and between fingers. (No timer? It takes about 20 seconds to hum the “Happy Birthday” song twice.)
• Rinse well with cold or warm water
• Dry your hands 

No soap and water available? Hand sanitizer is the second-best option. Use a product with no less than 60 percent alcohol.

In the kitchen, follow the CDC’s Four Steps to Food Safety: 

1. Clean your hands and surfaces often, especially before and after handling uncooked meat, poultry, flour, and eggs. Wash your utensils and kitchen surfaces after preparing a food item. Wash produce under cold running water before preparation. 
2. Separate food products to prevent cross-contamination. Use separate surfaces and utensils for raw and cooked ingredients.
3. Cook food to a safe internal temperature. The CDC maintains a detailed list of temperatures and foods for guidance.
4. Chill food promptly. Your refrigerator should be set to 40F or lower, and your freezer should be set to 0F.

Learn more at NutritionAction: 7 things to know about keeping your food safe

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