An E. coli outbreak that may be linked to fast-food chain Wendy's has spread to the states of New York and Kentucky, after reports of illnesses in Midwest states.

The Centers for Disease Control and Prevention said Thursday that 97 people have become ill, 43 have been hospitalized and 10 have developed a serious condition called hemolytic uremic syndrome, due to the outbreak.

Eighty-one percent of the people who said they were ill had said they ate at Wendy's. Many reported eating sandwiches with romaine lettuce.

The first illness was reported in late July.

"A specific food has not yet been confirmed as the source of this outbreak, but many sick people reported eating sandwiches with romaine lettuce at Wendy's restaurants in Indiana, Michigan, Ohio, and Pennsylvania before getting sick," the CDC said.

The CDC confirmed that "there is no evidence to indicate that romaine lettuce sold in grocery stores, served in other restaurants, or in people's homes is linked to this outbreak."

The CDC is not advising people to avoid Wendy's.

"While the CDC has not yet confirmed a specific food as the source of that outbreak, we have taken the precaution of removing the sandwich lettuce at some restaurants," Wendy's said Sunday in updated statement from Aug. 19. "The lettuce that we use in our salads is different, and is not affected by this action."

Symptoms of E. coli include diarrhea, high fever over 102 degrees Fahrenheit, vomiting, dehydration, and feeling dizzy.