UPDATE: The Centers for Disease Control is now urging consumers to avoid all types of romaine lettuce (not just chopped romaine) unless they can confirm that it did not come from the Yuma, Arizona, growing area.
Alaska, Arizona, California, Louisiana and Montana are now among the 16 states that have reported a collective 53 cases of E. coli, the CDC announced Wednesday. Idaho and Pennsylvania have been especially hard hit, with 10 and 12 respective cases reported.
Health authorities believe the illnesses can be traced back to chopped romaine lettuce from the Yuma, Arizona, region but have yet to identify any specific growers, suppliers or distributors as the source of the outbreak.
While the CDC has not issued a formal recall, it is urging consumers around the country to toss store-bought chopped romaine lettuce they may have at home. They should also sanitize any shelves or drawers where chopped romaine lettuce was recently stored.
Customers should also ask about the origin of any lettuce they encounter in stores or restaurants to ensure it is not chopped romaine from the Yuma area.
"If you cannot confirm the source of the romaine lettuce, do not buy it or eat it," the CDC cautioned.
In total, 31 people have been hospitalized in connection with the outbreak, five of whom have developed a form of kidney failure. No deaths have been reported.
According to the CDC, 95 percent of patients interviewed said they ate romaine lettuce the week before their illness began, mostly in restaurants. It appears they all ate chopped romaine; no illnesses have been linked to whole heads or hearts of romaine.