How disease detectives’ quick work traced deadly E. coli outbreak to McDonald’s Quarter Pounders

A recent E. coli outbreak linked to McDonald's Quarter Pounders has affected 90 individuals across 13 states, leading to over two dozen hospitalizations and one fatality. Health officials traced the outbreak to fresh slivered onions used in the burgers, supplied by Taylor Farms. The case began when several individuals, including a teenager in Colorado, experienced severe symptoms after consuming the popular burger, leading them to seek medical attention.

Through a rapid investigation, local and state health departments, along with the CDC, linked the cases using genetic sequencing data and detailed interviews with affected individuals. Colorado’s health department and the CDC collaborated to identify McDonald's Quarter Pounders as a common source, noting that the use of fresh beef and onions in this specific item may have contributed to the spread.

As a result, McDonald's has temporarily stopped selling Quarter Pounders in certain locations and has suspended its sourcing of onions from Taylor Farms indefinitely. The swift response by health authorities, including comprehensive testing and consumer interviews, enabled quick action to prevent further illnesses, though officials expect additional cases may still emerge as lab testing continues.