E. coli outbreak at McDonald’s: How did it spread and who is most vulnerable?

About 50 people have so far fallen ill after a food poisoning outbreak tied to McDonald’s Quarter Pounders was reported in the US. The outbreak has been linked to a common type of E. coli bacteria that can cause serious illness and death.
E. coli is a type of bacteria found in the environment, including water, food and in the intestines of people and animals. There are many kinds of harmless E. coli, but a few types can make people seriously ill.
The McDonald’s outbreak is caused by E. coli O157:H7, which produces a toxin that causes dangerous diarrhea and can lead to kidney failure and other serious problems.
A preliminary investigation suggests raw slivered onions served on Quarter Pounders are a likely source of the outbreak.
People can get sick from E. coli poisoning when they consume contaminated foods or through contact with animals, the environment or other people who are infected.
Reports suggest that health officials initially focused on fresh slivered onions and beef patties as the possible sources of the McDonald’s outbreak. But the beef patties are an unlikely source because of federal requirements for testing meat and McDonald’s protocols that call for cooking it to a temperature that kills the bacteria. The onions are served raw.
Particularly vulnerable are young children, older people or those with weakened immune systems.
Symptoms occur quickly, within a day or two of eating contaminated food, and typically include fever, vomiting, diarrhea or bloody diarrhea and signs of dehydration — little or no peeing, increased thirst and dizziness.
The infection can cause a type of serious kidney injury, especially in kids younger than 5. E coli poisoning in young children requires immediate medical attention.
The type of bacteria implicated in this outbreak causes about 74,000 infections in the U.S. annually, leading to more than 2,000 hospitalizations and 61 deaths each year, according to the CDC. In general, E. coli infections were lower in 2023 than in recent years and cases of severe kidney injury caused by the bacteria remained stable, according to latest federal data.