The E. coli outbreak linked to McDonald's Quarter Pounder hamburgers has now sickened 75 people, an increase of 26 since the outbreak was revealed on Wednesday, according to the federal Centers for Disease Control (CDC).
Illnesses started on dates ranging from September 27, 2024, to October 10, 2024. Of 61 people with information available, 22 have been hospitalized, and two people developed hemolytic uremic syndrome, a serious condition that can cause kidney failure.
One death has been reported from an older adult in Colorado; that person was not one of those who developed HUS.
The specific locations associated with the people who became sick have not been disclosed.
The outbreak now includes people in 13 states, up from 10 on Wednesday:
- Colorado
- Iowa
- Kansas
- Michigan
- Missouri
- Montana
- Nebraska
- New Mexico
- Oregon
- Utah
- Washington
- Wisconsin
- Wyoming
As of Friday, October 25, 2025, the CDC says there have been 13 reported cases of E.coli in Montana associated with the outbreak. The five states with the most cases are:
- Colorado: 26
- Montana: 13
- Nebraska: 11
- Wyoming: 5
- New Mexico: 5
According to the CDC, 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.
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 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.
While the investigation continues, McDonald's said earlier this week that it has stopped using those onions in the affected states. Additionally, Taylor Farms, a supplier of onions for the fast food chain, has initiated a voluntary recall.
"Diced onions and other types of beef patties used at McDonald’s have not been implicated in this outbreak," the federal Food & Drug Administration said.
The CDC says that 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.
The true number of sick people in this outbreak is also likely much higher than the number reported. This is because many people recover without medical care and are not tested for E. coli.
E. coli can cause severe stomach cramps and bloody or watery diarrhea. Some people may also experience vomiting or a fever. Symptoms typically start three to four days after ingesting the bacteria and most people typically recover within five to seven days.
The CDC recommends you call your healthcare provider if you have recently eaten a McDonald's Quarter Pounder and are experiencing symptoms of E. coli infection.
