Chopped romaine lettuce is the likely cause of an E. coli outbreak that has sickened 35 people in 11 states, and restaurants, retailers and consumers are being advised to throw away all chopped romaine.

Twenty-six of 28 sick people interviewed reported consuming chopped romaine in the week before their illness started, according to the Centers for Disease Control and Prevention.

As of April 12, no definitive source for the infected romaine had been found, but it is thought to have been grown in the Yuma, Arizona, region.

Twenty-two people had been hospitalized as of April 12. At that time, no fatalities had been reported.