An E. coli outbreak linked to McDonald’s Quarter Pounder burgers in the US has sickened at least 49 people and caused one death. So far, cases have been reported in ten states, with the most illnesses in Colorado and Nebraska.

On Tuesday, the U.S. Centers for Disease Control and Prevention posted a food safety alert announcing it was investigating a multistate outbreak of E. coli O157:H7 infections linked to contaminated McDonald’s Quarter Pounders.

The CDC called the outbreak “severe” in a news release, adding that McDonald’s has temporarily removed the suspect ingredients.

Escherichia coli (E. coli) is a bacterium that occurs in the intestines of humans and animals. Some species, such as E. coli O157:H7, can produce potent toxins that can cause serious and potentially fatal illness. Symptoms include bloody diarrhea, severe stomach cramps and vomiting.

McDonald’s E. coli Outbreak 2024

At least 49 cases of E. coli have been reported in 10 states so far in this outbreak, but “the actual number of sick people is likely much higher,” the CDC said.

Everyone interviewed as part of the study reported eating a McDonald’s hamburger before developing symptoms, with Quarter Pounders particularly mentioned.

In a statement released on October 22, McDonald’s said it is “taking swift and decisive action.”

Quarter Pounders are temporarily off sale at McDonald’s stores in 11 states, according to the CDC, and investigators are trying to determine which specific ingredient or ingredients are contaminated with E. coli.

Two ingredients used in Quarter Pounders are currently under investigation: fresh chopped onions and quarter-pound beef patties, the CDC said.

TODAY, on October 23, McDonald’s US President Joe Erlinger addressed the outbreak, stating that consumers can “confidently go to McDonald’s today” and eat the classics without getting sick.

“Food safety is our top priority at McDonald’s,” said Erlinger.

One person has died and ten have been hospitalized

There has been one death of an older adult in Colorado due to the outbreak. At least 10 people have been hospitalized, including one child who developed hemolytic uremic syndrome (HUS), a serious condition that can lead to kidney failure, the CDC said.

The people who became ill range in age from 13 to 88 years.

The illnesses linked to this outbreak started between September 27, 2024 and October 11, 2024. It is also possible that there are more recent illnesses that have yet to be reported, as it can take three to four weeks to link an individual’s illness to an outbreak, according to the CDC.

McDonald’s E. coli outbreak hits states

The outbreak has affected 10 states so far, with Colorado reporting the highest number of cases, followed by Nebraska and Wisconsin, according to the latest data from the CDC.

States affected and number of diseases reported:

• Colorado: 26
• Nebraska: 9
• Wisconsin: 4
• Iowa: 1
• Kansas: 1
• Missouri: 1
• Montana 1
• Oregon: 1
• Utah: 1
• Wyoming: 1

“This outbreak may not be limited to states with known illnesses, and the actual number of sick people is likely much higher than the reported number,” the CDC said on its website.

If you have questions about specific cases in your state, contact your state’s Department of Health, the CDC advised in a news release.

States where McDonald’s has removed Quarter Pounders from the menu

As the investigation into the outbreak continues, McDonald’s stores in multiple states have temporarily stopped selling Quarter Pounder beef patties and fresh-cut onions.

The quarter pound patties are only used on Quarter Pounders, and the chopped onions are “primarily used on Quarter Pounders and not on other menu items,” according to the CDC.

McDonald’s stores in the following states (or parts of states) have temporarily removed Quarter Pounders from their menus:

• Colorado
• Kansas
• Utah
• Wyoming

Servings of:

• Idaho
• Iowa
• Missouri
• Montana
• Nebraska
• Nevada
• New Mexico

What is E.coli?

E. coli is a type of bacteria found in the environment, food, water and in the digestive tract of people and animals, according to the CDC. Although most types of E. coli are harmless or cause mild diarrhea, some types can cause serious illness.

Certain strains, such as E. coli O157:H7, can produce potent Shiga toxins that can cause life-threatening illnesses. The most common Shiga toxin-producing strain in the US is E. coli O157:H7, which has been implicated in the McDonald’s Quarter Pounder outbreak.

E. coli O157:H7 causes an estimated 73,000 illnesses per year in the US

How do you get E.coli?

People can be exposed to E. coli by eating or drinking contaminated food or water. The main food sources for outbreaks of Shiga-producing E. coli are raw or undercooked ground beef, raw vegetables, and raw milk or cheese.

Transmission can also occur through touching the feces or contaminated surfaces of an infected person, according to the Cleveland Clinic. This can be the result of poor hygiene after using the toilet, changing diapers and before eating.

According to the CDC, some people are more likely to become infected with E. coli. This includes children under 5 years old, adults 65 years and older, people with weak immune systems and international travelers.

Symptoms of E. coli infection

Symptoms of infection with E. coli O157:H7 include:

• Stomach cramps, which can be severe
• Bloody or watery diarrhea
• Vomiting
• Low fever

According to the CDC, symptoms usually begin three to four days after ingesting the bacteria from contaminated food.

Most people will recover within a week, but some people may develop dehydration or life-threatening complications, including hemolytic uremic syndrome, which can lead to kidney failure.

The CDC is urging anyone who has recently eaten a McDonald’s Quarter Pounder and experienced severe symptoms to call their healthcare provider.

If you experience signs of dehydration (reduced urination, dry mouth, dizziness), severe vomiting, or a fever over 104 degrees Fahrenheit, seek immediate medical attention and tell the healthcare provider what you ate.