Investigation Details

September 26, 2019

CDC and several states, along with the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS) and the U.S. Food and Drug Administration (FDA), investigated a multistate outbreak of Listeria infections linked to deli-sliced meats and cheeses.

Public health investigators used 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 technique called whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. WGS performed on Listeria isolated from ill people in this outbreak showed that they were closely related genetically. This means that people in this outbreak were more likely to share a common source of infection.

As of September 26, 2019, a total of 10 people infected with the outbreak strain of Listeria monocytogenes were reported from 5 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Listeria specimens from ill people were collected from November 13, 2016 to June 20, 2019. Ill people ranged in age from 40 to 88 years, with a median age of 64. Fifty percent were female. All 10 people (100%) were hospitalized. One death was reported from Michigan.

Investigation of the Outbreak

Epidemiologic and laboratory evidence indicated that deli-sliced meats and cheeses might have been contaminated with Listeria monocytogenes and made people sick.

In interviews, ill people answered questions about the foods they ate and other exposures in the four weeks before they became ill. Of 8 people interviewed, 5 (63%) reported eating products sliced at a deli counter, including meats and cheeses. Delis where ill people shopped served many brands of products and there was limited information available about the brands ill people bought.

USDA-FSIS and FDA evaluated records collected by state inspectors from delis where ill people ate to determine whether a common meat or cheese product was served at the delis. The analysis of the available documentation did not identify a common product.

The outbreak strain of Listeria monocytogenes was identified in samples from meat sliced at a deli, and from deli counters in multiple retail locations in New York and Rhode Island. WGS showed that the Listeria from these samples was closely related genetically to the Listeria from ill people. This result provided more evidence that people in this outbreak got sick from eating deli-sliced products. The investigation did not identify a common product that was sliced or prepared in the delis.

This outbreak is a reminder that deli products, such as sliced meats and cheeses, can have Listeria bacteria. People who are at higher risk for Listeria infections should avoid eating lunch meats, cold cuts, or other deli meats, unless they are heated to an internal temperature of 165°F or until steaming hot just before serving.