The Effects of Excluding Infected Foodworkers on Norovirus Burden in the U.S. Open Access

Yang, Wen (2015)

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Noroviruses are the most commonly reported cause of acute gastroenteritis in the United States. Analyses of norovirus outbreak data indicate infected foodworkers to cause the majority of foodborne norovirus outbreaks. A deterministic, population-based compartmental model was used to assess variable compliance with the current FDA Food Code recommendations for all workers infected with norovirus to stay home from work while they are experiencing symptoms as well as ≥ 48 hours after their symptoms subside. We modeled the number and proportion of norovirus cases averted, in comparison to a baseline scenario assuming exclusion of 66.7% of symptomatic foodworkers and 0% of asymptomatic foodworkers nationally. Our findings underscored the increased benefit of excluding asymptomatic foodworkers in addition to symptomatic foodworkers. Assuming the referent is true, a maximum of 14.7 million cases have already been avoided annually. By excluding 100% of symptomatic foodworkers, 8.3 million norovirus cases can be averted annually. By also excluding 100% of asymptomatic foodworkers for 2 days, 9.5 million norovirus cases can be avoided annually. When varying the proportion of symptomatic foodworker exclusion (Φ1) for any given proportion of asymptomatic foodworker exclusion for 2 days (Φ2 and Φ3, where Φ2=Φ3), 18-64 year-olds experienced the largest change in number of cases averted per year (absolute range of 13.0 million cases) while 0-4 year-olds experienced the smallest change (absolute range of 3.2 million cases). When varying Φ2 and Φ3 for 2 days for any given Φ1, 18-64 year-olds experienced the largest change in number of cases averted (reaching 700,124 at 66.67% symptomatic foodworker exclusion) while 0-4 year-olds or 65+ year-olds experienced the smallest change (reaching 168,422 cases at 66.67% symptomatic foodworker exclusion), depending on Φ1. In comparison, 65+ year-olds experienced the greatest change in proportion of baseline cases averted while 0-4 year-olds experienced the smallest change, no matter if we varied Φ1 or varied Φ2 and Φ3, holding the other constant. Our findings support the current FDA Food Code recommendation as well as future modeling of interventions that target foodworkers and address reasons for which foodworkers decide to work while ill.

Table of Contents

Chapter I: Literature Review. 1

Chapter II. 10

Introduction. 10

Methods. 13

Results. 18

Discussion. 22

References. 26

Tables. 29

Figures. 33

Chapter III: Public Health Implications. 38

Appendix. 39

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