Characterizing Norovirus Seasonality in High Income Countries Using Wavelet Analysis Public

Abstract

Norovirus is the leading cause of sporadic cases and outbreaks of acute gastroenteritis worldwide. The rapidly evolving genome of norovirus has resulted in the numerous worldwide pandemics with novel strains emerging every 3-4 years. Regional comparisons of seasonality could identify unique signatures in norovirus incidence patterns that correspond with molecular changes in circulating and emerging norovirus strains. There is a significant amount of evidence for the wintertime seasonality but there is limited data on inter-season variation as well as country level comparisons. We used data from the national surveillance systems from four high income countries, Germany, Japan, United Kingdom and United States, to estimate and compare the seasonality of norovirus incidence. Descriptive and wavelet analyses were used to identify country specific seasonal variations in emergent and non-emergent strain years, as well as country level comparisons of norovirus incidence. All four countries showed strong evidence for 12- month periodicity with peaks during the winter months, November to February, and low level or disappearance in summer months. There was variation in the effect of the emergence on a new strain on the norovirus incidence in different countries. The emergence of the 2012 Sydney strained was associated with increased levels of norovirus burden in all four countries. Other emergent strains such as 2006/7ab and 2010 New Orleans produced a significant increase of incidence in some countries but not all. Peak month and month of 50% case burden did not show strong correlation between countries. Norovirus is endemic globally but does not have a uniform effect. Identifying characteristic changes in norovirus incidence in years with or without novel variant strains may allow earlier warning for pandemic potential outbreaks and improve transmission prevention and control measures.

Table of Contents

Table of Contents

Background…………...………………………………………………………………….………..3

Introduction……………...………………………………………………..……………….……..6

Methods…………………………………………………………………………..…………………8

Results……………..………………………………………………………………...……………..10

Discussion………….……………………………………………………………...……….………13

References…………...…...……………………………………………………….………..……..15

Figures

Figure 1….…….….……………………………………………………………...…….….17

Figure 2…….……….………...……………………………………………………….….18

Figure 3………………..…………………..……………..………………….………...….21

Figure 4….…….……..…………………………………..………………….…………….21

Figure 5….….………………………………………………………………………..…….22

Figure 6………......…………………………………………………………………….….23

Figure 7……….……...…………………………………..………………………….…….24

Figure 8…………………………………………………..……………………………..….25

Tables

Table 1…….….……………….……………………………………………………..........19

Table 2………………..………...………………………………………………...…….....20

Table 3………………..………...…………………………………………………..……...20

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Global Epidemiology - MPH & MSPH
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Biology, Virology
Mot-clé	Seasonality Norovirus Wavelet Analysis
Committee Chair / Thesis Advisor	Benjamin Lopman, PhD, Emory University
Committee Members	Kristin Bratton Nelson, PhD, Emory University

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