Norovirus disease today
Authors: P. Pothier, L. Kaiser
Journal: Clinical Microbiology and Infection (2014)

Human noroviruses were difficult to identify before the molecular era in diagnostics, but they now constitute the leading cause of acute gastroenteritis in all age groups. These environmentally stable and highly contagious viruses spread through water or food, or directly from person to person. Outbreaks of gastroenteritis can occur in all regions of the world and throughout the year, but most norovirus gastroenteritis cases occur during the winter period; hence the originally proposed name of ‘winter vomiting disease’. The four reviews of this special issue provide updates on the current knowledge about the evolution of noroviruses, the burden of noroviruses in immunocompetent or immunocompromised people, and the control of norovirus disease. The study of White [1White P Evolution of norovirus.Clin Microbiol Infect. 2014; 20: 741-745Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar] shows the mechanisms of the evolution of noroviruses, especially genogroup II genotype 4 (GII.4), the most prevalent norovirus. This genotype undergoes antigenic drift on the external domain of its capsid protein (P2 domain), allowing it to escape herd immunity. This immune selection drives antigenic changes that contribute to the emergence of novel GII.4 variants. This mechanism has been observed in the last two decades in the GII.4 norovirus that was responsible for the last six major gastroenteritis pandemics. Besides this antigen drift mechanism, RNA recombination is the other major driving force that contributes to the evolution of contemporary norviruses. RNA recombination is promoted by the presence of a breakpoint at the open reading frame (ORF) 1–ORF2 overlap. The studies by Belliot et al. [2Belliot G Lopman BA Ambert-Balay K Pothier P The burden of norovirus gastroenteritis: an important foodborne and health-care-related infection.Clin Microbiol Infect. 2014; 20: 724-730Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar] and Green [3Green KY Norovirus infection in immunocompromised hosts.Clin Microbiol Infect. 2014; 20: 717-723Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar] show the clinical aspects of the disease and the burden of norovirus gastroenteritis. Diarrhoea and vomiting are the predominant symptoms; others may include abdominal cramps, fever, headache, chills, and myalgia. Fortunately, the illness is usually mild, and lasts for <3 days. Nevertheless, some population groups are at higher risk or are more vulnerable than others. Young children have the highest incidence of norovirus gastroenteritis, which causes up to 200 000 deaths of children aged <5 years in developing countries. Elderly people living in nursing homes constitute the other largest population group with a particularly high risk of winter outbreaks of norovirus gastroenteritis. Dissemination of human noroviruses in these two populations is favoured by the extreme genetic heterogeneity within these viruses and the emergence of new variants. One other population, the immunocompromised, is also more vulnerable. In such individuals, norovirus can cause chronic infection, which can become debilitating and life-threatening. Besides their clinical burden, norovirus infections result in significant costs for healthcare and the food industry. Without effective treatment or vaccination, infection control is based on the strict application of hygiene programmes, ranging from cleaning to isolation and cohorting. The study of Barclay et al. [4Barclay L Park GW Vega E et al.Infection control for norovirus.Clin Microbiol Infect. 2014; 20: 731-740Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar] reviews infection control guidelines for norovirus, and addresses future strategies regarding these. The authors have no conflicts of interest to declare in relation with this article.