If you've recently bought chopped romaine lettuce in bags or salad mixes, do not eat the products. Throw them out.

That's the advice from state and federal health officials as they work to track down the source of an E. coli outbreak that has sickened at least 35 people in 11 states, including nine in Pennsylvania and seven in New Jersey.

The U.S. Centers for Disease Control and Prevention says the romaine came from the Yuma, Ariz., area, but the agency has not yet identified a common grower, supplier, distributor, or brand.

However, a Pennsylvania food-manufacturing company last week voluntarily recalled more than 8,700 pounds of ready-to-eat salad kits after learning from its romaine lettuce supplier that contamination with E. coli was a possibility. Fresh Foods Manufacturing of Freedom, Beaver County, said the recalled products, labeled "Great to Go by Market District," have not been linked to any illnesses. The mixes, including Caesar salads with chicken, ham, or bacon, were shipped to retail locations in Pennsylvania, Indiana, Ohio, and West Virginia. The recall was announced by the U.S. Department of Agriculture's Food Safety and Inspection Service on Saturday.

Health officials in Delaware, which has no reports of illness, also have issued warnings. Consumers who have purchased chopped romaine lettuce "should not eat it and instead throw it away, even if some of it was eaten and no one has gotten sick," the Delaware Division of Public Health said Tuesday in a news release.

Symptoms of E. coli infection include diarrhea, severe stomach cramps, and vomiting.  Five percent to 10 percent of infections progress to a type of life-threatening kidney failure.

Because of the lag time between identification of an infection and the report to the CDC, the agency has not updated the case count since April 12. Of the 35 confirmed reports, Pennsylvania had the highest number with nine. Twenty-two people who were sickened have been hospitalized, three with kidney failure. No deaths have been reported.

The Pennsylvania Department of Health said it was "working closely with our federal partners, including the Centers for Disease Control and Prevention and the Food and Drug Administration, as part of this investigation."