During the last week of November and the beginning of December, 2006, state and local health departments in New Jersey, New York, Pennsylvania, and Delaware began receiving reports of E. coli O157:H7 illnesses among patrons of Taco Bell restaurants. The Centers for Disease Control and Prevention (CDC) joined an investigation into the outbreak, and on December 13, 2006, announced that at 71 people had become sick with an illness associated with the Taco Bell restaurant outbreak. Of those 71, 53 people had been hospitalized and 8 developed hemolytic uremic syndrome.
The investigation into the Taco Bell E. coli outbreak focused first on green onions as the source, but CDC and Food and Drug Administration (FDA) investigators later changed their focus to lettuce. According to an FDA news release on December 13, FDA investigators were working to trace back the potentially contaminated lettuce that had been served at Taco Bell restaurants to the farm where the lettuce was grown.