CDC on McDonald's (MCD) E. coli Outbreak: True number of sick people likely much higher than the number reported
CDC, public health and regulatory officials in several states, the U.S. Food and Drug Administration (FDA), and the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS) are collecting different types of data to investigate a multistate outbreak of E. coli O157:H7 infections.
Epidemiologic data show that Quarter Pounder hamburgers served at McDonald’s (NYSE: MCD) are contaminated with E. coli and are making people sick. Early information from FDA indicates onions may be a source of this outbreak. Investigators from all agencies are working quickly to determine the contaminated ingredient.
Epidemiologic data
As of October 24, 75 people infected with the outbreak strain of E. coli O157:H7 have been reported from 13 states. Illnesses started on dates ranging from Sept 27, 2024, to October 10, 2024. Of 61 people with information available, 22 have been hospitalized, and 2 people developed hemolytic uremic syndrome, a serious condition that can cause kidney 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.
Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the week before they got sick. This information provides clues to help investigators identify the source of the outbreak.
The table below has information about sick people in this outbreak (“n” is the number of people with information available for each demographic).
Demographics
Information
Age
(n=74)
Range from 13 to 88 years
Median age of 29
Sex
(n=75)
40% female
60% male
Race
(n=59)
95% White
3% African American/Black
0% Native American or Alaska Native
0% Asian
0% Native Hawaiian or other Pacific Islander
2% reported more than one race
Ethnicity
(n=55)
91% non-Hispanic
9% Hispanic
State and local public health officials are interviewing people about the foods they ate in the week before they got sick. Of the 42 people interviewed, all 42 (100%) report eating at McDonald's, and 39 people report eating a beef hamburger. Of 36 people who remember the specific beef hamburger they ate at McDonald's, 31 (86%) report eating a Quarter Pounder hamburger. Some people in this outbreak reported traveling to other states before their illness started. At least three people ate at McDonald's during their travel.
Traceback Information
Investigators are working to determine if the slivered onions or beef patties in Quarter Pounder burgers are the specific source of this outbreak.
Preliminary traceback and distribution information reviewed by FDA shows that slivered onions served on Quarter Pounders are a likely source of contamination. FDA is working quickly to confirm that these onions are a source of this outbreak and to determine if these onions were served or sold at other businesses.
Taylor Farms, the supplier of slivered onions for affected McDonald’s locations initiated a recall of yellow onions. Customers were contacted directly and asked to remove products. FDA is working closely with the implicated firms and will continue to provide updates including any additional recalls that might be needed for businesses who received recalled onions.
FSIS is conducting traceback on hamburger patties served at McDonald’s to determine if ground beef is a source of illness.
Public health actions
McDonalds 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. Quarter Pounders will not be available for sale temporarily in some states. Call your healthcare provider if you ate a McDonald’s Quarter Pounder hamburger and have severe E. coli symptoms.