title: A Stochastic Model to Assess the Effect of Meat Inspection Practices on the Contamination of the Pig Carcasses.
abstract: The objective of meat inspection is to promote animal and public health by preventing, detecting, and controlling hazards originating from animals. With the improvements of sanitary level in pig herds, the hazards profile has shifted and the inspection procedures no longer target major foodborne pathogens (i.e., not risk based). Additionally, carcass manipulations performed when searching for macroscopic lesions can lead to cross-contamination. We therefore developed a stochastic model to quantitatively describe cross-contamination when consecutive carcasses are submitted to classic inspection procedures. The microbial hazard used to illustrate the model was Salmonella, the data set was obtained from Brazilian slaughterhouses, and some simplifying assumptions were made. The model predicted that due to cross-contamination during inspection, the prevalence of contaminated carcass surfaces increased from 1.2% to 95.7%, whereas the mean contamination on contaminated surfaces decreased from 1 logCFU/cm² to -0.87 logCFU/cm², and the standard deviations decreased from 0.65 to 0.19. These results are explained by the fact that, due to carcass manipulations with hands, knives, and hooks, including the cutting of contaminated lymph nodes, Salmonella is transferred to previously uncontaminated carcasses, but in small quantities. These small quantities can easily go undetected during sampling. Sensitivity analyses gave insight into the model performance and showed that the touching and cutting of lymph nodes during inspection can be an important source of carcass contamination. The model can serve as a tool to support discussions on the modernization of pig carcass inspection.
authors.affiliation: Laboratory of Veterinary Epidemiology (Epilab), Department of Preventive Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: de Freitas Costa
authors.affiliation: Laboratory of Veterinary Epidemiology (Epilab), Department of Preventive Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Luis Gustavo
authors.initials: LG
authors.lastname: Corbellini
authors.affiliation: Laboratory of Veterinary Epidemiology (Epilab), Department of Preventive Veterinary Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Ana Paula Serafini Poeta
authors.initials: APSP
authors.lastname: da Silva
authors.affiliation: Technical University of Denmark - National Food Institute, Søborg, Denmark.
authors.forename: Maarten
authors.initials: M
authors.lastname: Nauta
mesh_terms: D000003:Abattoirs; D000818:Animals; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis* / Q000517:prevention & control*; D005513:Food Inspection / Q000592:standards*; D005516:Food Microbiology; D006801:Humans; D008198:Lymph Nodes / Q000382:microbiology; D008460:Meat / Q000382:microbiology*; D015233:Models, Statistical; D015995:Prevalence; D011336:Probability; D012475:Salmonella; D012480:Salmonella Infections / Q000517:prevention & control / Q000635:transmission; D012481:Salmonella Infections, Animal / Q000453:epidemiology*; D012680:Sensitivity and Specificity; D013269:Stochastic Processes; D013552:Swine
keywords: Carcass inspection; cross-contamination; mathematical modeling