MADISON, Wis. (AP) — Federal and state health officials say a multistate outbreak of salmonella bacteria that is resistant to several drugs has been linked to infected dairy bull calves purchased in Wisconsin.

The Centers for Disease Control and Prevention says 21 people have been infected in eight states from Jan. 11 through Oct. 24. Eight of the 21 people sickened were hospitalized, but no deaths have been reported.

Those who were sickened ranged in age from 1 year to 72. Wisconsin has the most cases with 12 people infected in eight counties.

The CDC says its investigation identified dairy bull calves from livestock markets in Wisconsin as the likely source of infections. Minnesota and South Dakota each have two cases and California, Iowa, Idaho, Missouri and Oklahoma each have one.