An outbreak of food-borne illness linked to romaine lettuce has spread to four states and sickened at least 23 people, the Centers for Disease Control and Prevention said.

Tennessee is the latest state to confirm a case of E.coli 0145, which has already sickened 10 people in Michigan, eight in Ohio and four in New York. The confirmed cases rose to 23, the CDC said Wednesday, from the 19 it reported last week. The agency is also reporting seven more probable cases which have not been confirmed yet.

No deaths have been reported so far.

Investigators have linked the illnesses to tainted romaine lettuce grown on a farm in Yuma, Arizona.

Two distributors - Freshway Foods and Vaughan Foods - have voluntarily recalled bagged lettuce that was harvested from that farm.

Ohio-based Freshway's recall came a day after the New York state Public Health Laboratory in Albany reported finding E.coli O145 in an unopened bag of Freshway Foods shredded romaine lettuce, the U.S. Food and Drug Administration said.

The company said the recalled lettuce had "best if used by" dates of May 12 or earlier and was sold to wholesalers, food service outlets, and some in-store salad bars and delis in: Alabama, Connecticut, the District of Columbia, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, West Virginia, and Wisconsin.

Vaughan Foods, an Oklahoma-based supplier of processed and packaged lettuce, has also recalled lettuce grown on the same Arizona farm with "use by" dates of May 9 and May 10.

No E.coli illnesses have been traced back to Vaughan, the FDA said.

E.coli 0145 can cause symptoms that range from mild diarrhea to abdominal cramps and bloody stool. It can also cause a potentially life-threatening complication called hemolytic uremic syndrome, or HUS.

In HUS, the body's blood-clotting mechanisms are altered, causing blocked circulation or bleeding in the brain or kidneys.

Though most healthy adults recover within a week, young children and the elderly are most at risk of developing HUS. Federal health authorities are encouraging anyone with such symptoms to contact a health care provider immediately