The U.S. Food and Drug Administration (FDA) has closed its investigation into an E. coli outbreak across McDonalds stores in West and Midwest U.S. The outbreak has been linked to slivered yellow onions served on McDonald’s Quarter Pounder burgers. 

While the outbreak was not officially confirmed in any product or environmental samples, the FDA concluded the yellow onions were likely to be the source after Taylor Farms initiated a voluntary recall on yellow onions the supplier had provided McDonalds and other food service customers. On 22 October, the FDA opened its investigation and a traceback confirmed that fresh onions served in the McDonald’s burgers were the cause. 

As of yesterday (3 December), 104 people across 14 states were affected by the outbreak. 34 of these were hospitalised, four developed hemolytic uremic syndrome (HUS), and another person died. Now that consumers are aware of the outbreak, and the product recalled, the U.S. Centers for Disease Control and Prevention (CDC) now considers the outbreak to be over and the case closed.