title: A practical framework for the construction of a biotracing model: application to Salmonella in the pork slaughter chain.
abstract: A novel purpose of the use of mathematical models in quantitative microbial risk assessment (QMRA) is to identify the sources of microbial contamination in a food chain (i.e., biotracing). In this article we propose a framework for the construction of a biotracing model, eventually to be used in industrial food production chains where discrete numbers of products are processed that may be contaminated by a multitude of sources. The framework consists of steps in which a Monte Carlo model, simulating sequential events in the chain following a modular process risk modeling (MPRM) approach, is converted to a Bayesian belief network (BBN). The resulting model provides a probabilistic quantification of concentrations of a pathogen throughout a production chain. A BBN allows for updating the parameters of the model based on observational data, and global parameter sensitivity analysis is readily performed in a BBN. Moreover, a BBN enables "backward reasoning" when downstream data are available and is therefore a natural framework for answering biotracing questions. The proposed framework is illustrated with a biotracing model of Salmonella in the pork slaughter chain, based on a recently published Monte Carlo simulation model. This model, implemented as a BBN, describes the dynamics of Salmonella in a Dutch slaughterhouse and enables finding the source of contamination of specific carcasses at the end of the chain.
authors.affiliation: Laboratory for Zoonoses and Environmental Microbiology, National Institute for Public Health and the Environment, Bilthoven, The Netherlands. joost.smid@rivm.nl
authors.forename: J H
authors.initials: JH
authors.lastname: Smid
authors.forename: A N
authors.initials: AN
authors.lastname: Swart
authors.forename: A H
authors.initials: AH
authors.lastname: Havelaar
authors.forename: A
authors.initials: A
authors.lastname: Pielaat
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D005516:Food Microbiology; D008461:Meat Products / Q000382:microbiology*; D008962:Models, Theoretical; D011336:Probability; D018570:Risk Assessment; D012475:Salmonella / Q000302:isolation & purification*; D013552:Swine