Epidemiology and Infection

Systematic Review

The epidemiology of published norovirus outbreaks: a review of risk factors associated with attack rate and genogroup

J. E. MATTHEWSa1, B. W. DICKEYa1, R. D. MILLERa1, J. R. FELZERa1, B. P. DAWSONa1, A. S. LEEa1, J. J. ROCKSa1, J. KIELa1, J. S. MONTESa1, C. L. MOEa1, J. N. S. EISENBERGa2 and J. S. LEONa1 c1

a1 Hubert Department of Global Health, Emory University Rollins School of Public Health, Atlanta, GA, USA

a2 Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA


The purpose of this study was to examine global epidemiological trends in human norovirus (NoV) outbreaks by transmission route and setting, and describe relationships between these characteristics, viral attack rates, and the occurrence of genogroup I (GI) or genogroup II (GII) strains in outbreaks. We analysed data from 902 reverse transcriptase–polymerase chain reaction-confirmed, human NoV outbreaks abstracted from a systematic review of articles published from 1993 to 2011 and indexed under the terms ‘norovirus’ and ‘outbreak’. Multivariate regression analyses demonstrated that foodservice and winter outbreaks were significantly associated with higher attack rates. Foodborne and waterborne outbreaks were associated with multiple strains (GI+GII). Waterborne outbreaks were significantly associated with GI strains, while healthcare-related and winter outbreaks were associated with GII strains. These results identify important trends for epidemic NoV detection, prevention, and control.

(Received October 05 2011)

(Revised January 17 2012)

(Accepted February 01 2012)

(Online publication March 27 2012)


c1 Author for correspondence: J. S. Leon, Emory University, Hubert Department of Global Health, Mailstop 1518-002-7BB, 1518 Clifton Road NE, Atlanta, GA 30322, USA. (Email: juan.leon@emory.edu)


† These authors contributed equally to this work.