Key points
Epidemiologic and traceback data show that fresh, slivered onions served at McDonald’s were the likely source of this outbreak. Affected onions served at McDonald's locations were recalled and are past shelf life.
November 13, 2024
CDC, public health and regulatory officials in several states, the U.S. Food and Drug Administration (FDA) are collecting different types of data to investigate a multistate outbreak of E. coli O157:H7infections.
Epidemiologic and traceback data show that fresh, slivered onions served at McDonald's were the likely source of this outbreak.
Epidemiologic data
As of November 13, a total of 104 people infected with the outbreak strain 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 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).
State and local public health officials are interviewing people about the foods they ate in the week before they got sick. Of the 81 people interviewed, 80 (99%) report eating at McDonald's. Seventy-five people were able to remember specific menu items they ate at McDonald's. Of 75 people with information, 63 (84%) reported a menu item containing fresh slivered onions.
Some people in this outbreak reported traveling to other states before their illness started. At least seven people ate at McDonald's during their travel.
Laboratory information
FDA tested recalled onions and one sample tested positive for non-O157:H7 Shiga toxin-producing E. coli. The E.coli found in onions was not the outbreak strain and no human illnesses have been linked to this strain. Additional testing results will be released when available by FDA.
Public health actions
Because these onions are recalled and past shelf life, it is not necessary to avoid eating onions or other foods made with onions. Call your healthcare provider if you have severe E. coli symptoms.
Previous updates
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:H7infections.
Epidemiologic and traceback data show that fresh, slivered onions served at McDonald's were the likely source of this outbreak.
Epidemiologic data
As of October 30, 90 people infected with the outbreak strain of E. coli O157:H7 have been reported from 13 states. Illnesses started on dates ranging from September 27, 2024, to October 16, 2024. Of 83 people with information available, 27 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).
State and local public health officials are interviewing people about the foods they ate in the week before they got sick. Of the 62 people interviewed, all 62 (100%) report eating at McDonald's. Fifty-eight people were able to remember specific menu items they ate at McDonald's. Forty-eight of 58 people (83%) reported a menu item containing fresh, slivered onions. Forty-six of 58 people (79%) reported a menu item made with fresh quarter pound beef patties. Overall, three people reported menu items that contained fresh, slivered onions, but not fresh quarter pound beef patties. One person reported a menu item with a fresh quarter pound beef patty but without fresh, slivered onions
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 and laboratory data
FDA has initiated inspections at a Taylor Farms processing center in Colorado and an onion grower of interest in Washington state. FDA is unable to implicate a grower at this time.
On October 22, Taylor Farms, the supplier of slivered onions for affected McDonald's locations, initiated a recall of yellow onions. Customers were contacted directly by Taylor Farms 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.
On October 22, the Colorado Department of Agriculture (CDA) laboratories analyzed subsamples from all the lots of McDonald's brand fresh and frozen beef patties collected from various McDonald's locations in Colorado and found them to be negative for E. coli. All beef testing has been completed.
FSIS has conducted a thorough investigation, including traceback of beef patties served on Quarter Pounders at McDonald's, and evidence does not point to ground beef as the likely source of contamination. FSIS used specific meal information reported by ill people to trace beef patties through the supply chain to the establishments where they were produced and did not identify a beef source. FSIS will continue to work closely with federal and state partners.
Public health actions
Because onions have been recalled, it is not necessary to avoid eating onions or other foods made with onions. Call your healthcare provider if you have severe E. coli symptoms.
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 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 September 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).
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.
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 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 22, 49 people infected with the outbreak strain of E. coli O157:H7 have been reported from 10 states. Illnesses started on dates ranging from September 27, 2024, to October 11, 2024. Of 28 people with information available, 10 have been hospitalized, and 1 person developed hemolytic uremic syndrome, a serious condition that can cause kidney failure. One death has been reported from an older adult in Colorado. This is not the same person with 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).
State and local public health officials are interviewing people about the foods they ate in the week before they got sick. Of the 18 people interviewed, all 18 (100%) report eating at McDonald’s, and 16 people report eating a beef hamburger. Of 14 people who remember the specific beef hamburger they ate at McDonald’s, 12 (86%) report eating a Quarter Pounder hamburger. Some people in this outbreak reported traveling to other states before their illness started. At least one person 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.
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.