Since September 2015, CDC has been collaborating with public health officials in several states, the U.S. Food and Drug Administration (FDA), and the Public Health Agency of Canada to investigate a multistate outbreak of Listeria monocytogenes infections (listeriosis).

Fifteen people infected with the outbreak strain of Listeria have been reported from eight states since July 5, 2015, an increase of three cases since the last update on January 22. All 15 people were hospitalized, including one person from Michigan who died as a result of listeriosis. One illness was reported in a pregnant woman. The number of ill people reported from each state is as follows: Connecticut (1), Indiana (1), Massachusetts (1), Michigan (4), Missouri (1), New Jersey (1), New York (5), and Pennsylvania (1). Whole genome sequencing has been performed on clinical isolates from all ill people and has shown that the isolates are highly related genetically.

According to the Public Health Agency of Canada, there are seven people in five Canadian provinces infected with the same outbreak strain of Listeria. Laboratory tests performed on clinical isolates from ill people in Canada showed that the isolates are highly related genetically to Listeria isolates from ill people in the United States.

Epidemiologic and laboratory evidence indicate that packaged salads produced at the Dole processing facility in Springfield, Ohio and sold under various brand names are the likely source of this outbreak.