Last week, the Centers for Disease Control and Prevention issued a warning that chopped romaine lettuce originating from Yuma could be making people sick nationwide. The agency is now expanding its warning.

Based on reports from Alaska, where people got sick from heads of lettuce, the CDC now warns against eating all types of romaine lettuce from the Yuma, Arizona growing region.

The warning now includes whole heads and hearts of romaine lettuce, in addition to chopped romaine and salad mixes containing romaine. Laura Gieraltowski is an epidemiologist at the CDC.

“To get our advice out there again, if people have romaine lettuce at home and they don't know where its from, just throw it away and don't eat it," she said.

Gieraltowski said this particular strain of E. coli can be virulent. Those who have eaten the contaminated produce are hospitalized more often than expected and some have developed kidney failure.