title: Comparison of public health impact of Listeria monocytogenes product-to-product and environment-to-product contamination of deli meats at retail.
abstract: This study compared the relative public health impact in deli meats at retail contaminated with Listeria monocytogenes by either (i) other products or (ii) the retail environment. Modeling was performed using the risk of listeriosis-associated deaths as a public health outcome  of interest and using two deli meat products (i.e., ham and turkey, both formulated without growth inhibitors) as model systems. Based on reported data, deli meats coming to retail were assumed to be contaminated at a frequency of 0.4%. Three contamination scenarios were investigated: (i)  a baseline scenario, in which no additional cross-contamination occurred at retail, (ii) a scenario in which an additional 2.3% of products were cross-contaminated at retail due to transfer of L. monocytogenes cells from already contaminated ready-to-eat deli meats, and (iii) a scenario  in which an additional 2.3% of products were contaminated as a result of cross-contamination from a contaminated retail environment. By using a previously reported L. monocytogenes risk assessment model that uses product-specific growth kinetic parameters, cross-contamination of deli  ham and turkey was estimated to increase the relative risk of listeriosis-associated deaths by 5.9- and 6.1-fold, respectively, for contamination from other products and by 4.9- and 5.8-fold, respectively, for contamination from the retail environment. Sensitivity and scenario analyses indicated  that the frequency of cross-contamination at retail from any source (other food products or environment) was the most important factor affecting the relative risk of listeriosis-associated deaths. Overall, our data indicate that retail-level cross-contamination of ready-to-eat deli meats with  L. monocytogenes has the potential to considerably increase the risk of human listeriosis cases and deaths, and thus precise estimates of cross-contamination frequency are critical for accurate risk assessments.
authors: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA. akp@umd.edu
authors: Abani K
authors: AK
authors: Pradhan
authors: Renata
authors: R
authors: Ivanek
authors: Yrjö T
authors: YT
authors: Gröhn
authors: Robert
authors: R
authors: Bukowski
authors: Martin
authors: M
authors: Wiedmann
mesh_terms: D003132:Commerce; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D008088:Listeriosis / Q000517:prevention & control; D008461:Meat Products / Q000382:microbiology*; D011634:Public Health; D018570:Risk Assessment