Outbreak Investigation Updates by Date

April 17, 2019

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

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 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 are closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.

As of April 15, 2019, 8 people infected with the outbreak strain of Listeria monocytogenes have been reported from 4 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 March 4, 2019. Ill people range in age from 40 to 88 years, with a median age of 57. Thirty-eight percent are female. All 8 people (100%) have been hospitalized. One death has been reported from Michigan.

Investigation of the Outbreak

Epidemiologic and laboratory evidence indicates that deli-sliced meats and cheeses might be contaminated with Listeria monocytogenes and could make 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 6 people interviewed, 5 (83%) reported eating products sliced at a deli counter, including meats and cheeses. Delis where ill people shopped served many different brands of products and there is limited information about the brands ill people bought.

USDA-FSIS and FDA evaluated records state inspectors collected 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 could not identify a common product. USDA-FSIS and FDA will continue to assist with the investigation should additional information become available.

The outbreak strain of Listeria monocytogenes has been 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 strain from these samples is closely related genetically to the Listeria strain from ill people. This result provides more evidence that people in this outbreak got sick from eating deli-sliced products. At this time, the investigation has not identified 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.