The Centers for Disease Control and Prevention (CDC) has declared the conclusion of the E. coli O157:H7 outbreak linked to McDonald’s Quarter Pounder hamburgers. The outbreak, which began in late September 2024, affected 104 individuals across 14 states, resulting in 34 hospitalizations and one fatality—a 78-year-old man from Colorado.
Epidemiological and traceback investigations identified fresh, slivered onions supplied by Taylor Farms as the likely source of contamination. These onions were used in Quarter Pounders and other menu items. In response, McDonald’s promptly halted the use of the implicated onions on October 22, 2024, and temporarily suspended Quarter Pounder sales in the affected regions. The company has since resumed sales, now utilizing onions from a different supplier.
The U.S. Food and Drug Administration (FDA) conducted tests on samples from Taylor Farms but did not detect the outbreak strain of E. coli. Despite this, the collaborative efforts of the CDC, FDA, and state health departments led to the conclusion that the contaminated onions were the outbreak’s source. No new cases have been reported since the removal of the affected onions from McDonald’s restaurants.
McDonald’s has implemented additional safety measures to prevent future incidents, including enhanced supplier protocols and more rigorous food safety training for employees. The company is also investing $100 million in marketing and franchisee support to rebuild customer trust and ensure the safety of its menu offerings.
This outbreak underscores the importance of stringent food safety practices and prompt response to contamination events to protect public health.
