Nears and Nors Merge: A Preliminary Analysis

Introduction:  The National Environmental Assessment Reporting System (NEARS) managed by the National Center for Environmental Health’s Safe Food Team, and the National Outbreak Reporting System (NORS) managed by the National Center for Emerging Zoonotic and Infectious Diseases are CDC’s two primary foodborne illness reporting systems. Each system is designed to collect different information; while NORS collects clinical and epidemiological data on foodborne illness outbreaks, NEARS collects environmental data related to foodborne illness outbreaks. Previous food safety studies have used each of these datasets, yet no known studies exist that utilize both datasets.

Purpose:  This study is based on the merged datasets and aims to describe restaurant-related norovirus outbreaks using NEARS data (2009 to 2014) and NORS outbreak data (2009 to 2014). Descriptive analyses and inferential statistics help to provide more information about the foodborne illness outbreaks during 2009 to 2014.

Methods:  Descriptive statistics include mean, median, and distribution statistics of characteristics of outbreak restaurants. Cross-tabulation statistics show mean norovirus cases by outbreak restaurant characteristics and food safety policies. Lastly, inferential statistics examine statistically significant relationships between norovirus cases and outbreak restaurant food safety policies. The data were merged, cleaned, and analyzed using Stata SE 13.

Results:  Preliminary results indicate that some restaurant policies are statistically significantly associated with norovirus outbreak size. Particularly, restaurants with ill food worker communication policies had fewer average confirmed primary norovirus cases than restaurants without these policies.

Significance:  The decision to merge the NEARS and NORS datasets is primarily motivated by the aim to expand food safety analysis possibilities. Currently, no known dataset includes both food safety environmental and epidemiology indicators, so a merge allows CDC researchers to conduct analytic studies to examine the relationship between food safety environmental and etiologic variables of interest and thus identify effective interventions and reduce outbreaks.