The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) announced on Tuesday that they are conducting an investigation into an E. coli outbreak connected to Quarter Pounder burgers sold at McDonald’s in 10 different states.

According to the CDC, at least 49 individuals have fallen ill across 10 states, resulting in 10 hospitalizations and one death. The Colorado Department of Public Health identified that the deceased individual was an “older person with underlying conditions” from Colorado.

The CDC has yet to identify the specific contaminated ingredient, but McDonald’s released a statement on Tuesday, indicating that an early investigation showed “a subset of illnesses” was associated with slivered onions from a supplier catering to three of its distribution centers.

The FDA stated they are working promptly to confirm if these onions are linked to the outbreak and to check if these onions were distributed to other businesses as well.

Here’s a look at the E. coli outbreak connected to Quarter Pounders and its impact on public health.

E. coli Outbreak Map

States Reporting E. coli Cases as of October 22

The CDC listed the states where illnesses have been reported:

• Colorado
• Iowa
• Kansas
• Montana
• Missouri
• Nebraska
• Oregon
• Utah
• Wisconsin
• Wyoming

States Where Quarter Pounder Sales Have Been Halted

McDonald’s announced that they have temporarily stopped the sale of Quarter Pounders in the following states:

• Colorado
• Kansas
• Utah
• Wyoming

Furthermore, sales have been suspended in parts of:

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

Cesar Piña, McDonald’s North America Chief Supply Chain Officer, stated that they are collaborating closely with their suppliers to restore Quarter Pounder availability in the upcoming weeks, although the timing will vary by location. He emphasized that all other menu items remain unaffected by this outbreak.

What is E. coli? What Are the Symptoms?

Escherichia coli (E. coli) refers to a group of bacteria that typically live harmlessly in the intestines of humans and animals. However, some types can lead to mild to life-threatening gastrointestinal issues if ingested, as noted by the CDC.

E. coli strains that cause diarrhea mostly spread through food or water contaminated by feces. For example, food handlers may unintentionally transmit the bacteria by not washing their hands properly after using the restroom. Additionally, animals like cattle can also transmit E. coli to food and crops.

Symptoms of E. coli infection may include severe stomach cramps, diarrhea (which can be bloody), and vomiting, according to the CDC.

The agency recommends seeking immediate medical care if you experience:

• Diarrhea along with a fever above 102°F
  • Diarrhea lasting more than three days without improvement
  • Bloody diarrhea
• Excessive vomiting that prevents you from holding down liquids
• Signs of dehydration, such as:
  • Reduced urination
  • Dry mouth and throat
  • Dizziness when standing