Norovirus Illness Is a Global Problem: Emergence and Spread of Norovirus GII.4 Variants, 2001–2007

TL;DR: Establishing a global NoV network by which data on strains with the potential to cause pandemics can be rapidly exchanged may lead to improved prevention and intervention strategies, and show notable differences in geographic prevalence.

Abstract: Background Noroviruses (NoVs) are the most common cause of viral gastroenteritis Their high incidence and importance in health care facilities result in a great impact on public health Studies from around the world describing increasing prevalence have been difficult to compare because of differing nomenclatures for variants of the dominant genotype, GII4 We studied the global patterns of GII4 epidemiology in relation to its genetic diversity Methods Data from NoV outbreaks with dates of onset from January 2001 through March 2007 were collected from 15 institutions on 5 continents Partial genome sequences (n = 775) were collected, allowing phylogenetic comparison of data from different countries Results The 15 institutions reported 3098 GII4 outbreaks, 62% of all reported NoV outbreaks Eight GII4 variants were identified Four had a global distribution-the 1996, 2002, 2004, and 2006b variants The 2003Asia and 2006a variants caused epidemics, but they were geographically limited Finally, the 2001 Japan and 2001Henry variants were found across the world but at low frequencies Conclusions NoV epidemics resulted from the global spread of GII4 strains that evolved under the influence of population immunity Lineages show notable (and currently unexplained) differences in geographic prevalence Establishing a global NoV network by which data on strains with the potential to cause pandemics can be rapidly exchanged may lead to improved prevention and intervention strategies