On Tuesday, the CDC reported 49 cases and one death linked to McDonald’s Quarter Pounders tainted with E. coli. In the past week, hundreds of waffle and pancake products were voluntarily recalled due to potential Listeria contamination.

In 10 states throughout the country, 49 people have gotten ill and one has died after an E. coli outbreak at McDonald’s. Infected people reported eating a McDonald’s Quarter Pounder, and experts suspect the beef or the onions on the hamburger sickened folks.

Fresh onions are the likely source of an E. coli outbreak at McDonald's restaurants that has sickened 49 people and killed one, the U.S. Department of Agriculture said late on Wednesday, alarming some McDonald's customers and other fast-food chains using onions as an ingredient.