Epidemiologic and traceback data show that fresh, slivered¹ onions served at McDonald's were the likely source of this outbreak.

As of November 13, a total of 104 people infected with the outbreak strain² of E. coli O157:H7 have been reported from 14 states. Illnesses started on dates ranging from September 12, 2024, to October 21, 2024. Of 98 people with information available, 34 have been hospitalized, and 4 people developed hemolytic uremic syndrome³, a serious condition that can cause kidney⁴ failure. One death has been reported from an older adult in Colorado. This person is not one of those who developed HUS.



The true number of sick people in this outbreak is likely much higher than the number reported, and the outbreak may not be limited to the states with known illnesses.

This is because many people recover without medical care and are not tested for E. coli. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.