A deadly E. coli outbreak linked to McDonald’s Quarter Pounder hamburgers has affected 49 people across 10 states. The Center for Disease Control and Prevention (CDC) is investigating the situation.
The outbreak, which began on September 27, 2024, has resulted in 10 hospitalizations, including one case of hemolytic uremic syndrome and one death. State health officials in Colorado alerted the CDC of an unusual increase in E. coli cases on October 10, with the CDC launching its investigation on October 15. Most of the illnesses have been concentrated in Colorado and Nebraska.
Epidemiological data shows that all 18 people interviewed reported eating at McDonald’s, with 86% specifically consuming a Quarter Pounder before becoming ill. The outbreak strain has been identified as E. coli O157:H7, the same strain linked to a 1993 Jack in the Box incident.
The 1993 Jack in the Box E. coli outbreak is considered one of the most significant foodborne illness incidents in the U.S. The crisis started when undercooked beef patties at the chain’s restaurants caused widespread contamination, leading to 732 confirmed cases of illness, 171 hospitalizations, and four deaths—mostly among children. This incident reshaped food safety standards, including stricter cooking temperatures and mandatory testing for E. coli. The outbreak also led to major legal action, resulting in a $50 million settlement for victims.
The restaurant chain initially tried to shift the blame to suppliers but eventually accepted responsibility, increased cooking temperatures, and overhauled food safety practices. Despite the devastation, Jack in the Box managed to recover financially and is now recognized as a leader in fast-food safety.
McDonald’s has taken precautionary measures by removing Quarter Pounders from menus in Colorado, Kansas, Utah, Wyoming, and portions of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, and Oklahoma. The company has also suspended using fresh slivered onions and quarter-pound beef patties in these locations. Preliminary investigations suggest the slivered onions, sourced from a single supplier serving three distribution centers, might be the likely source of contamination. However, federal regulators are also examining whether the hamburger patties could contribute to the outbreak.
The outbreak has impacted McDonald’s stock performance, with analysts downgrading the company’s shares as they await further clarity. The timing coincides with the recent launch of McDonald’s $5 value meals and the acceleration of U.S. comparable sales.
The CDC expects additional cases may be reported, as it typically takes three to four weeks to determine if a sick person is part of an outbreak. The most recent case was reported on October 11.
