(CNN) Ground beef is the food responsible for a mystery E. coli outbreak involving 109 cases of illness in six states, according to preliminary evidence, the US Centers for Disease Control and Prevention said Friday.

"Ill people in this outbreak report eating ground beef at home and in restaurants," the CDC said in its outbreak update.

No single supplier, distributor or brand has been identified as the source of the outbreak. Therefore, no recall has been issued, and the CDC is not recommending that consumers avoid ground beef at this time or that restaurants stop serving it.

Illnesses are now being reported in six states : Georgia, Kentucky, Ohio, Tennessee, Virginia and Indiana.

That's one more state and 13 more illnesses since the previous update reported by the CDC on Tuesday.

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