In August 2017 the CDC announced an outbreak of Salmonella Heidelberg linked to contact with dairy bull calves. A total of 56 people infected with the outbreak strains of Salmonella Heidelberg were reported from 15 states. Illness onset dates ranged from January 27, 2015 to November 25, 2017. Seventeen persons were hospitalized. No deaths were reported.

Of the 54 people interviewed, 34 (63%) reported contact with dairy bull calves or other cattle. Some of the ill people interviewed reported that they became sick after their dairy bull calves became sick or died.

Antibiotic resistance testing conducted by CDC on clinical isolates from ill people shows that the isolates were resistant to multiple types of antibiotics.