Removing food products with a concentration of Listeria monocytogenes higher than 1 colony forming unit per gram (CFU/g) from the market may reduce L. monocytogenes contamination by 15–88 percent and reduce the number of associated listeriosis cases by 55.9–100 percent in the U.S., a recent study suggests. The study also demonstrated a notable decrease (4.9–62.9 percent) of L. monocytogenes prevalence in U.S. ready-to-eat (RTE) products over the last five years due to control efforts.
A quantitative risk assessment and literature review were conducted to estimate the probability of L. monocytogenes infection among the U.S. population from consuming contaminated products, as well as to approximate the prevalence of L. monocytogenes in food products at the retail level worldwide and in the U.S. The results found that, at present, listeriosis may affect up to 32.9 percent of the U.S. population that is considered highly susceptible to infection. The highly susceptible population was attributed to 46.9–80.1 percent of the total cases. Additionally, the study gauged that the overall prevalence of L. monocytogenes in food products could range from 1.4–9.9 percent worldwide and 0.5–3.8 percent in the U.S.
RTE products were highlighted as a high-risk food type for L. monocytogenes contamination. Of the estimated listeriosis cases in the U.S., the majority were attributed to deli meats (greater than 90 percent of cases) followed by RTE salads (3.9–4.5 percent), soft and semi-soft cheeses (0.5–1.0 percent), RTE seafood (0.5–1.0 percent), and frozen vegetables (0.2–0.3 percent).
To reduce the public health impact of L. monocytogenes and improve the availability of enumeration data, the study’s authors suggest the introduction of lot-by-lot testing and the definition of allowable quantitative regulatory limits for low-risk RTE commodities.