Attribution of Pediatric Acute Gastroenteritis Episodes and Emergency Department Visits to Norovirus Genogroups I and II.

Affiliation

Tarr GAM(1), Pang XL(2), Zhuo R(3), Lee BE(4), Chui L(2), Ali S(5), Vanderkooi OG(6), Michaels-Igbokwe C(7), Tarr PI(8), MacDonald SE(9), Currie G(7), MacDonald J(10), Kim K(11), Freedman SB(12).
Author information:
(1)Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota, USA.
(2)Department of Laboratory Medicine and Pathology, University of Alberta and Alberta Precision Laboratories-ProvLab, Edmonton, Alberta, Canada.
(3)Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada.
(4)Department of Pediatrics, Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.
(5)Departments of Pediatrics and Emergency Medicine, Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.
(6)Departments of Pediatrics, Microbiology, Immunology and Infectious Diseases, Pathology and Laboratory Medicine, and Community Health Sciences, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.
(7)Departments of Pediatrics and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.
(8)Division of Gastroenterology, Hepatology, & Nutrition, Washington University School of Medicine, St Louis, Missouri, USA.
(9)Faculty of Nursing, University of Alberta, Edmonton, Alberta, Canada.
(10)Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
(11)Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada.
(12)Sections of Pediatric Emergency Medicine and Gastroenterology, Department of Pediatrics, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.

Abstract

BACKGROUND: Norovirus is a leading cause of acute gastroenteritis. With vaccines in development, population-based estimates of norovirus burden are needed to identify target populations, quantify potential benefits, and understand disease dynamics. METHODS: We estimated the attributable fraction (AF) for norovirus infections in children, defined as the proportion of children testing positive for norovirus whose gastroenteritis was attributable to norovirus. We calculated the standardized incidence and emergency department (ED) visit rates attributable to norovirus using provincial gastroenteritis visit administrative data. RESULTS: From 3731 gastroenteritis case patients and 2135 controls we determined that the AFs were 67.0% (95% confidence interval [CI], 31.5%-100%) and 91.6% (88.8%-94.4%) for norovirus genogroups I (GI) and II (GII), respectively. Norovirus GII AF varied by season but not age. We attributed 116 episodes (95% CI, 103-129) and 59 (51-67) ED visits per 10 000 child-years to norovirus GII across all ages, accounting for 20% and 18% of all medically attended gastroenteritis episodes and ED visits, respectively. CONCLUSIONS: In children, a large proportion of norovirus GII detections reflect causation, demonstrating significant potential for norovirus GII vaccines. Seasonal variation in the norovirus GII AF may have implications for understanding the role asymptomatic carriage plays in disease dynamics.