Challenges and opportunities for risk- and systems-based control of Listeria monocytogenes transmission through food.

Listeria monocytogenes contamination of ready-to-eat (RTE) food products and food-associated built environments (e.g., processing facilities) represents a food safety issue with major public health and business risk implications. A number of factors make L. monocytogenes control a particular challenge, including (i) its frequent presence in different environments, (ii) its propensity for establishing persistence in food-associated environments, (iii) its ability to grow under a variety of stressful conditions, and (iv) its ability to cause severe illness, particularly in immunocompromised individuals and pregnant people. Key sources of L. monocytogenes contamination of RTE foods are food-associated built environments. However, raw materials can also be an important source, particularly for products without a "kill step" (e.g., fresh produce, raw dairy products, cold-smoked seafood). While certain RTE foods (e.g., deli meats, soft cheeses, produce) have commonly been linked to listeriosis outbreaks, cases, and recalls, a number of factors will influence the specific public health risk a given RTE food represents, including the likelihood of contamination, ability to support L. monocytogenes growth, and consumer-related factors (including consumption by pregnant or immunocompromised individuals). Consequently, a risk-based approach presents the most appropriate strategy to minimize the public health and business impact of L. monocytogenes. Key challenges to control L. monocytogenes include (i) development and implementation of food safety systems that prevent L. monocytogenes persistence in food-associated built environments, (ii) minimizing L. monocytogenes contamination of raw material sources, (iii) implementation of effective root cause analysis procedures, (iv) minimizing L. monocytogenes growth in finished product, and (v) consumer education.