Epidemiologic evidence indicates that contact with pig ear dog treats is the likely source of this outbreak.

In interviews, ill people answered questions about animal contact in the week before they became ill. Thirty-four (89%) of 38 ill people reported contact with a dog before getting sick. Of 24 people with available information, 17 (71%) reported contact with pig ear dog treats or with dogs who were fed pig ear dog treats. Both of these proportions are significantly higher than the results from a survey of healthy people who reported contact with dogs (61%) or handling dog treats, such as pig ears (16%), in the week before interview.

Officials from the Michigan Department of Agriculture and Rural Development gathered pig ear dog treats at retail locations where ill people reported buying the products. They sampled pig ears for Salmonella. Although the outbreak strain was not identified, other strains of Salmonella were. Investigators are checking to see if any human illnesses are linked to those strains. Retail locations where sampling occurred have removed pig ears from shelves.

A common supplier of pig ear dog treats has not been identified.

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are investigating a multistate outbreak of multidrug-resistant Salmonella I 4,[5],12:i:- infections linked to contact with pig ear dog treats.

As of July 2, 2019, a total of 45 people infected with the outbreak strain of Salmonella I 4,[5],12:i:- have been reported from 13 states.

California – 1

Illinois – 3

Indiana – 3

Iowa – 12

Kansas – 3

Massachusetts – 2

Michigan – 7

Missouri – 3

New York – 6

North Dakota – 1

Pennsylvania – 2

South Carolina – 1

Wisconsin – 1

Total – 45

Illnesses started on dates ranging from November 18, 2018, to June 13, 2019. Ill people range in age from less than 1 year to 81 years, with a median age of 23. Half (50%) of ill people are female. Of 39 ill people with information available, 12 (31%) have been hospitalized. No deaths have been reported.

Illnesses might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks.