title: Quantitative Risk Assessment of Norovirus Transmission in Food Establishments: Evaluating the Impact of Intervention Strategies and Food Employee Behavior on the Risk Associated with Norovirus in Foods.
abstract: We developed a quantitative risk assessment model using a discrete event framework to quantify and study the risk associated with norovirus transmission to consumers through food contaminated by infected food employees in a retail food setting. This study focused on the impact of ill food workers experiencing symptoms of diarrhea and vomiting and potential control measures for the transmission of norovirus to foods. The model examined the behavior of food employees regarding exclusion from work while ill and after symptom resolution and preventive measures limiting food contamination during preparation. The mean numbers of infected customers estimated for 21 scenarios were compared to the estimate for a baseline scenario representing current practices. Results show that prevention strategies examined could not prevent norovirus transmission to food when a symptomatic employee was present in the food establishment. Compliance with exclusion from work of symptomatic food employees is thus critical, with an estimated range of 75-226% of the baseline mean for full to no compliance, respectively. Results also suggest that efficient handwashing, handwashing frequency associated with gloving compliance, and elimination of contact between hands, faucets, and door handles in restrooms reduced the mean number of infected customers to 58%, 62%, and 75% of the baseline, respectively. This study provides quantitative data to evaluate the relative efficacy of policy and practices at retail to reduce norovirus illnesses and provides new insights into the interactions and interplay of prevention strategies and compliance in reducing transmission of foodborne norovirus.
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Duret
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, USA.
authors.forename: Régis
authors.initials: R
authors.lastname: Pouillot
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Fanaselle
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, USA.
authors.forename: Efstathia
authors.initials: E
authors.lastname: Papafragkou
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, USA.
authors.forename: Girvin
authors.initials: G
authors.lastname: Liggans
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, USA.
authors.forename: Laurie
authors.initials: L
authors.lastname: Williams
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, USA.
authors.forename: Jane M
authors.initials: JM
authors.lastname: Van Doren
mesh_terms: D000465:Algorithms; D017250:Caliciviridae Infections / Q000635:transmission*; D004196:Disease Outbreaks; D005502:Food; D005506:Food Contamination; D005511:Food Handling; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000453:epidemiology; D005759:Gastroenteritis / Q000821:virology; D006801:Humans; D015233:Models, Statistical; D029322:Norovirus; D016273:Occupational Exposure; D015995:Prevalence; D012147:Restaurants; D018570:Risk Assessment / Q000379:methods*; D013997:Time Factors
keywords: Discrete event model; microbial risk assessment; norovirus; retail food establishment