Emergency Department Visit Data for Rapid Detection and Monitoring of Norovirus Activity, United States

Brian Rha,Soyoun Park,Sherry Burrer,Umesh D Parashar,Tarak Trivedi,Benjamin A Lopman

doi:10.3201/eid1908.130483

Abstract

Noroviruses are the leading cause of gastroenteritis in the United States, but timely measures of disease are lacking. BioSense, a national-level electronic surveillance system, assigns data on chief complaints (patient symptoms) collected during emergency department (ED) visits to 78 subsyndromes in near real-time. In a series of linear regression models, BioSense visits mapped by chief complaints of diarrhea and nausea/vomiting subsyndromes as a monthly proportion of all visits correlated strongly with reported norovirus outbreaks from 6 states during 2007–2010. Higher correlations were seen for diarrhea (R = 0.828–0.926) than for nausea/vomiting (R = 0.729–0.866) across multiple age groups. Diarrhea ED visit proportions exhibited winter seasonality attributable to norovirus; rotavirus contributed substantially for children <5 years of age. Diarrhea ED visit data estimated the onset, peak, and end of norovirus season within 4 weeks of observed dates and could be reliable, timely indicators of norovirus activity.

Highlights

Noroviruses are the leading cause of gastroenteritis in the United States, but timely measures of disease are lacking
The models can be expressed with the following formulas: pCCx,y = α + (β1 × Noroy) + (β2 × Rotay) + (β3 × Timey) for models in which the rotavirus term was significant and positive, and pCCx,y = α + (β1 × Noroy) + (β2 × Timey) for all other models, where pCC is the proportion of emergency department (ED) visits mapped by chief complaint to the subsyndrome of interest, Noro is the count of reported norovirus outbreaks, Rota is the proportion of positive rotavirus antigen tests, in age group x and year-month y, the intercept α represents the background proportion of ED visits mapped by chief complaint to the subsyndrome of interest, and Time is the sequential variable for month of study included to account for secular trends
For children

Summary

Introduction

Noroviruses are the leading cause of gastroenteritis in the United States, but timely measures of disease are lacking. The Pearson correlation coefficient (R) and the coefficient of determination (R2) were calculated for each model across the 5 age groups to determine the strength and direction of the relationship between ED visits mapped by chief complaint to diarrhea or nausea/vomiting and norovirus outbreak data.

Results

Conclusion