A serious outbreak of E. coli O157:H7 has been traced to McDonald’s Quarter Pounder hamburgers, resulting in 75 reported illnesses, 22 hospitalizations, and one death across 13 states. Federal and state health officials are racing to identify the exact source of contamination, with preliminary investigations pointing to slivered onions as a potential culprit.
Outbreak spreads rapidly across western United States
The outbreak has primarily affected western states, with Colorado and Montana reporting the highest number of cases. Affected states include Colorado, Iowa, Kansas, Michigan, Missouri, Montana, Nebraska, New Mexico, Oregon, Utah, Washington, Wisconsin, and Wyoming.
Health officials warn that the true number of cases may be significantly higher, as many affected individuals recover without seeking medical attention or getting tested for E. coli. The most recent reported illness started on October 10, 2024.
McDonald’s takes immediate action to protect customers
In response to the outbreak, McDonald’s has temporarily suspended the sale of Quarter Pounders in Colorado, Kansas, Utah, Wyoming, and portions of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, and Oklahoma.
The fast-food chain has also stopped using fresh slivered onions and quarter-pound beef patties in the affected regions while investigators work to confirm the contaminated ingredient. Other menu items, including other burgers, remain unaffected and available for purchase.
Taylor Farms initiates voluntary onion recall
Taylor Farms, the supplier of slivered onions to the affected McDonald’s locations, has initiated a voluntary recall of certain yellow onions sent to food service operators. The FDA is working to determine if these onions were distributed to other businesses.
Preliminary traceback investigations suggest that the slivered onions used on Quarter Pounders are a likely source of contamination. However, investigators continue to examine all ingredients to ensure a comprehensive investigation.
Understanding E. coli O157:H7 infection risks
The strain involved in this outbreak, E. coli O157:H7, produces powerful Shiga toxins that can cause severe illness. One child has developed hemolytic uremic syndrome (HUS), a serious condition that can lead to kidney failure.
Common symptoms include severe stomach cramps, diarrhea (often bloody), and vomiting. Some individuals may experience a fever higher than 102°F. Symptoms typically appear 3-4 days after exposure to the bacteria.
Multiple agencies coordinate investigation efforts
The CDC, FDA, USDA FSIS, and state health officials are working together to investigate the outbreak. Their efforts include collecting and evaluating records, tracking distribution information, and conducting laboratory testing of samples.
McDonald’s is actively collaborating with investigation partners to identify the specific contaminated ingredient and prevent further illnesses. The company emphasizes that food safety remains its top priority.
When to seek medical attention
Health officials recommend contacting a healthcare provider immediately if you experience severe symptoms after consuming a Quarter Pounder. Warning signs include diarrhea lasting more than 3 days, bloody stools, high fever, or signs of dehydration.
Individuals with compromised immune systems, young children, and older adults face higher risks of developing severe complications from E. coli infections.
Preventive measures and food safety guidelines
While the investigation continues, consumers should follow basic food safety practices: thoroughly cook ground beef, wash fresh produce, and maintain proper hand hygiene. Restaurant operators should not sell or serve the recalled Taylor Farms yellow onions.
Food service establishments are advised to review their food handling procedures and ensure all employees follow proper hygiene protocols.
This outbreak serves as a reminder of the importance of robust food safety systems and rapid response protocols in protecting public health. As investigators work to contain the spread and prevent further illnesses, regular updates will be provided through the CDC and FDA websites.
