Listeria monocytogenes Outbreak Linked to Deli Meats

Written by Ryan Maus | Sep 4, 2024 6:39:07 PM

A recent outbreak of Listeria monocytogenes has caused 43 illnesses and three deaths across thirteen states and has been
linked with epidemiologic, laboratory, and traceback data to deli meats produced by one manufacturer. The investigation
initially implicated liverwurst from a retail store in Maryland and New York. The samples of unopened product tested positive for a strain of L. monocytogenes that matched the outbreak strain. The investigation into how the meat became contaminated is ongoing. Deli meats and cheeses have been involved in four prior outbreaks in the U.S. since 2018.

Recent Outbreaks of Listeria Infections Linked to Deli Meats and Cheese
Year	Product	Illness	Death	States Reporting
2022	Deli Meats & Cheese*	16	1	CA, IL, MA, MD, NJ, NY
2020	Deli Meats*	12	1	FL, LA, MA, NY
2019	Deli Meats and Cheese*	10	1	MA, MI, NJ, NY, PA
2018	Deli Ham	4	1	NC, VA

*A single deli or food source was not identified

In many multistate outbreaks involving deli meats and cheese, a single product manufacturer or point of contamination is not identified. The outbreak strain is often found in multiple sliced products at multiple deli locations. It can be difficult for investigators to identify the specific source of outbreaks linked to deli meats and cheeses because Listeria spreads easily between food and the deli environment, and it can live for a long time in deli display cases and on equipment. Cross contamination at a deli, through a slicer for example, could then implicate multiple products. However, a contaminated product from a manufacturer
likely introduced the outbreak strain of L. monocytogenes into the delis. FSIS provides Best Practices Guidance for Controlling Listeria monocytogenes in Retail Delicatessens.

Meat production in the U.S. is regulated by USDA-FSIS. HACCP plans are required and need to be validated to demonstrate that the HACCP system, as designed, can adequately control identified hazards to produce a safe product. Deli meats are considered ready-to-eat (RTE). If they are exposed to the environment after a lethality control, then they must also follow FSIS Compliance Guideline: Controlling Listeria monocytogenes in Post-lethality Exposed Ready-to-Eat Meat and Poultry Products. This includes applying product post-lethality treatments, incorporating an antimicrobial agent or process, implementing sanitation controls, or a combination thereof. Post lethality treatments were added in USDA guidelines recognizing the potential for cross contamination from the environment following a 1998-1999 outbreak involving hot dogs and deli meats contaminated with L. monocytogenes. The outbreak was traced to product contamination during construction. Work on the plant's air conditioning system generated dust that spread L. monocytogenes via airborne particles throughout the manufacturing area.

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