CDC, public health and regulatory officials in several states, and the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS) are investigating a multistate outbreak of Listeria monocytogenes infections.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting is performed on Listeria bacteria isolated from ill people by using a standardized laboratory and data analysis method called whole genome sequencing (WGS). CDC PulseNet manages a national database of these sequences that are used to identify possible outbreaks. WGS gives investigators detailed information about the bacteria causing illness. In this investigation, WGS showed that bacteria isolated from ill people were closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.

As of October 22, 2020, a total of 10 people infected with the outbreak strain of Listeria monocytogenes have been reported from three states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Listeria samples from ill people were collected from August 6, 2020, to October 3, 2020. Ill people range in age from 40 to 89 years, with a median age of 81 years. Eighty percent of ill people are female. All 10 ill people were hospitalized. One death has been reported from Florida.

Investigation of the Outbreak
Epidemiologic evidence shows that deli meat is a likely source of this outbreak.

State and local public health officials interviewed ill people about the foods they ate in the month before they became ill. Of the nine people interviewed, all reported eating Italian-style deli meats, such as salami, mortadella, and prosciutto. They reported purchasing prepackaged deli meats and meats sliced at deli counters at various locations.

Listeria bacteria can spread easily to other foods and surfaces. The bacteria in a contaminated deli product may spread to other deli meats and cheeses in shared display cases or equipment at deli counters.  A traceback investigation is ongoing to determine if there is a specific type of deli meat or a common supplier linked to illness.

Source: CDC