title: Multiple-Strain Approach and Probabilistic Modeling of Consumer Habits in Quantitative Microbial Risk Assessment: A Quantitative Assessment of Exposure to Staphylococcal Enterotoxin A in Raw Milk.
abstract: Quantitative microbial risk assessment (QMRA) models are extensively applied to inform management of a broad range of food safety risks. Inevitably, QMRA modeling involves an element of simplification of the biological process of interest. Two features that are frequently simplified or disregarded are the pathogenicity of multiple strains of a single pathogen and consumer behavior at the household level. In this study, we developed a QMRA model with a multiple-strain approach and a consumer phase module (CPM) based on uncertainty distributions fitted from field data. We modeled exposure to staphylococcal enterotoxin A in raw milk in Lombardy; a specific enterotoxin production module was thus included. The model is adaptable and could be used to assess the risk related to other pathogens in raw milk as well as other staphylococcal enterotoxins. The multiplestrain approach, implemented as a multinomial process, allowed the inclusion of variability and uncertainty with regard to pathogenicity at the bacterial level. Data from 301 questionnaires submitted to raw milk consumers were used to obtain uncertainty distributions for the CPM. The distributions were modeled to be easily updatable with further data or evidence. The sources of uncertainty due to the multiple-strain approach and the CPM were identified, and their impact on the output was assessed by comparing specific scenarios to the baseline. When the distributions reflecting the uncertainty in consumer behavior were fixed to the 95th percentile, the risk of exposure increased up to 160 times. This reflects the importance of taking into consideration the diversity of consumers' habits at the household level and the impact that the lack of knowledge about variables in the CPM can have on the final QMRA estimates. The multiple-strain approach lends itself to use in other food matrices besides raw milk and allows the model to better capture the complexity of the real world and to be capable of geographical specificity.
authors.affiliation: Department DIVET, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Crotta
authors.affiliation: Department DIVET, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Rizzi
authors.affiliation: Lombardy and Emilia Romagna Experimental Zooprophylactic Institute, Via Bianchi 79, 25124 Brescia, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Varisco
authors.affiliation: Lombardy and Emilia Romagna Experimental Zooprophylactic Institute, Via Bianchi 79, 25124 Brescia, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Daminelli
authors.affiliation: Lombardy and Emilia Romagna Experimental Zooprophylactic Institute, Via Bianchi 79, 25124 Brescia, Italy.
authors.forename: Elena Cosciani
authors.initials: EC
authors.lastname: Cunico
authors.affiliation: Lombardy and Emilia Romagna Experimental Zooprophylactic Institute, Via Einstein, 26900 Lodi, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Luini
authors.affiliation: Agroscope, Institute for Food Sciences IFS, Schwarzenburgstrasse 161, 3003 Berne, Switzerland.
authors.forename: Hans Ulrich
authors.initials: HU
authors.lastname: Graber
authors.affiliation: Lombardy and Emilia Romagna Experimental Zooprophylactic Institute, Via Rovelli 53, 24100 Bergamo, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Paterlini
authors.affiliation: Veterinary Epidemiology, Economics and Public Health Group, The Royal Veterinary College, Hawkshead Lane, North Mymms, AL9 7TA, Hatfield, UK.
authors.forename: Javier
authors.initials: J
authors.lastname: Guitian
mesh_terms: D000818:Animals; D003258:Consumer Behavior; D003257:Consumer Product Safety; D004768:Enterotoxins / Q000302:isolation & purification*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D008892:Milk / Q000382:microbiology*; D015233:Models, Statistical; D008962:Models, Theoretical; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000302:isolation & purification
chemical_list: D004768:Enterotoxins; C026066:enterotoxin A, Staphylococcal