Risk assessment predicts most of the salmonellosis risk in raw chicken parts is concentrated in those few products with high-levels of high-virulent serotypes of Salmonella

Abstract

Salmonella prevalence has reduced in U.S. raw poultry products since adopting prevalence-based Salmonella performance standards, but human illnesses did not reduce proportionally. We used Quantitative Microbial Risk Assessment to evaluate public health risks of raw chicken parts contaminated with different levels of all Salmonella and specific high- and low-virulent serotypes. Lognormal Salmonella level distributions were fitted using data from 2012 USDA-FSIS Baseline Survey and 2023 USDA-FSIS HACCP verification sampling data. Three different dose-response (DR) models were used: Single DR for all serotypes, reduced virulence for Kentucky, multiple serotype- specific DR models. All scenarios found risk concentrated in the few products with high Salmonella levels. Using a single DR model with Baseline data (=-3.19, {sigma}=1.29), 68% and 37% of illnesses were attributed to the 0.7% and 0.06% of products > 1 and 10 CFU/g Salmonella, respectively. More recent HACCP data (=-4.85, {sigma}=2.44) showed that 99.9% and 99.6% of illnesses were attributed to the 2.3% and 0.8% of products > 1 and 10 CFU/g Salmonella, respectively. Scenarios with serotype-specific DR models showed more concentrated risk at higher levels. Baseline data showed 91.5% and 63.7% and HACCP data showed >99.9% and 99.9% of illnesses were attributed to products > 1 and 10 CFU/g Salmonella, respectively. Regarding serotypes, 0.003% and 0.3% of illnesses were attributed to the 0.2% and 0.7% of products with > 1 CFU/g of Kentucky, respectively, while 69% and 78.7% of illnesses were attributed to the 0.3% and 1.2% of products > 1 CFU/g containing either Enteritidis, Infantis, or Typhimurium using Baseline or HACCP input data, respectively. These results suggest public health risk in chicken parts is concentrated in the few finished products with high-levels and specifically high- levels of high-virulent serotypes. Low-virulent serotypes, such as Kentucky, are predicted to contribute to extremely few human cases.