title: An educationally inspired illustration of two-dimensional Quantitative Microbiological Risk Assessment (QMRA) and sensitivity analysis.
abstract: Quantitative Microbiological Risk Assessment (QMRA) is a structured methodology used to assess the risk involved by ingestion of a pathogen. It applies mathematical models combined with an accurate exploitation of data sets, represented by distributions and - in the case of two-dimensional Monte Carlo simulations - their hyperparameters. This research aims to highlight background information, assumptions and truncations of a two-dimensional QMRA and advanced sensitivity analysis. We believe that such a detailed listing is not always clearly presented in actual risk assessment studies, while it is essential to ensure reliable and realistic simulations and interpretations. As a case-study, we are considering the occurrence of listeriosis in smoked fish products in Belgium during the period 2008-2009, using two-dimensional Monte Carlo and two sensitivity analysis methods (Spearman correlation and Sobol sensitivity indices) to estimate the most relevant factors of the final risk estimate. A risk estimate of 0.018% per consumption of contaminated smoked fish by an immunocompromised person was obtained. The final estimate of listeriosis cases (23) is within the actual reported result obtained for the same period and for the same population. Variability on the final risk estimate is determined by the variability regarding (i) consumer refrigerator temperatures, (ii) the reference growth rate of L. monocytogenes, (iii) the minimum growth temperature of L. monocytogenes and (iv) consumer portion size. Variability regarding the initial contamination level of L. monocytogenes tends to appear as a determinant of risk variability only when the minimum growth temperature is not included in the sensitivity analysis; when it is included the impact regarding the variability on the initial contamination level of L. monocytogenes is disappearing. Uncertainty determinants of the final risk indicated the need of gathering more information on the reference growth rate and the minimum growth temperature of L. monocytogenes. Uncertainty in the dose-response relationship was not included in the analysis, hence the level of its influence cannot be assessed in the present research. Finally, a baseline global workflow for QMRA and sensitivity analysis is proposed.
authors.affiliation: Division of Mechatronics, Biostatistics and Sensors (MeBioS), Department of Biosystems, KU Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium.
authors.forename: G A
authors.initials: GA
authors.lastname: Vásquez
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Scientia Terrae Research Institute, Consortium for Industrial Microbiology and Biotechnology (CIMB), Thomas More, KU Leuven Association, Fortsesteenweg 30A, B-2860 Sint-Katelijne Waver, Belgium. Electronic address: pieter.busschaert@kuleuven.be.
authors.forename: P
authors.initials: P
authors.lastname: Busschaert
authors.affiliation: Division of Mechatronics, Biostatistics and Sensors (MeBioS), Department of Biosystems, KU Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium.
authors.forename: L U
authors.initials: LU
authors.lastname: Haberbeck
authors.affiliation: Laboratory of Food Microbiology and Food Preservation (LFMFP), Department of Food Safety and Food Quality, Ghent University, Belgium. Electronic address: Mieke.Uyttendaele@UGent.be.
authors.forename: M
authors.initials: M
authors.lastname: Uyttendaele
authors.affiliation: Division of Mechatronics, Biostatistics and Sensors (MeBioS), Department of Biosystems, KU Leuven, Willem de Croylaan 42, B-3001 Leuven, Belgium. Electronic address: annemie.geeraerd@kuleuven.be.
authors.forename: A H
authors.initials: AH
authors.lastname: Geeraerd
mesh_terms: D000818:Animals; D001530:Belgium; D003198:Computer Simulation; D005396:Fish Products / Q000382:microbiology; D005516:Food Microbiology / Q000379:methods*; D006801:Humans; D008089:Listeria monocytogenes / Q000254:growth & development; D008088:Listeriosis / Q000517:prevention & control*; D008962:Models, Theoretical; D009010:Monte Carlo Method; D018570:Risk Assessment
keywords: Listeria monocytogenes; QMRA; Sensitivity analysis; Smoked fish