In early March 2017, public health and regulatory officials in several states, the Centers for Disease Control and Prevention (CDC), and the US Food and Drug Administration (FDA) investigated an outbreak of Listeria monocytogenes infections. Investigators used epidemiologic evidence and laboratory results from the PulseNet system to identify case patients who were part of the outbreak. Ten people infected with the outbreak strain of Listeria were reported from four states, New York, Connecticut, Vermont and Florida. The Florida case had traveled to New York in the month before illness onset. Listeria specimens from ill people were collected from September 1, 2016 to March 13, 2017. Nine outbreak associated cases were hospitalized. Two people died.

Whole genome sequencing (WGS) performed on clinical isolates from all 8 case-patients showed that the isolates were closely related genetically, providing strong support that illnesses were linked to a common source.

The investigation was assigned CDC Cluster ID 1701MLGX6-3WGS.