WASHINGTON (AP) -- Wisconsin and Michigan appear to be the states hardest hit by illness believed to be linked with beef suspected of E. coli contamination.

Federal health officials say at least 23 people in nine states have become ill and 12 have been hospitalized, two of them suffering kidney failure.

According to the Centers for Disease Control and Prevention, the first reported illness began on April 2nd and the last on June 13th. Wisconsin and Michigan have each had six ill people identified by the CDC.

Other cases were reported in California, Maine, Minnesota, New Hampshire, New Jersey, New Mexico and New York.

The CDC did not specify the states in which people were hospitalized.

The victims may have become ill after eating beef produced by JBS Swift Beef Co. of Greeley, Colorado. The company has recalled more than 400,000 pounds of beef.