Norovirus infection Microchapters
Norovirus On the Web
American Roentgen Ray Society Images of Norovirus
Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
Norovirus is the cause of norovirus infection. Noroviruses (genus Norovirus) are a group of related, single-stranded RNA, nonenveloped viruses that cause acute gastroenteritis in humans. Noroviruses belong to the family Caliciviridae.
Norovirus is transmitted through person-to-person contact, food and water. Genotype GII.4 is mostly contact transmitted. Non-GII.4 genotypes such as GI.3, GI.6, GI.7, GII.3, GII.6 and GII.12 are mostly food-borne. Genogroup GI strains are more often transmitted through water. This is due to their higher stability in water compared to other strains of the virus.
Norovirus is among top ranks of food-borne viruses, globally. Transmission could occur in different stages of pre- and post-production of the food products. For instance, shellfish can be contaminated with fecal discharge in the water, fresh and frozen berries could be contaminated through water contaminated by sewage or contact during harvesting. Viral outbreaks through food-borne transmission can lead to a mixture of the viral strain and increased risk of genetic recombination. Studies show that about 7% of the foodborne outbreaks have a common source.
Less Common Causes
Norovirus also has a nosocomial transition, causing a major burden for health care services. Immunocompromised patients may develop numerous norovirus variations due to the chronic infection. This intra-host viral variation may lead to the appearance of variants not similar to any of the ones of previous outbreaks, thus can escape the herd immunity.
To date, animal norovirus strains have not been reported to infect human population, but there has been evidence of intra-species transmission. Human norovirus has been detected in the stools of pigs, cattle and dogs.
- ↑ 1.0 1.1 1.2 de Graaf M, van Beek J, Koopmans MP (2016). "Human norovirus transmission and evolution in a changing world". Nat Rev Microbiol. 14 (7): 421–33. doi:10.1038/nrmicro.2016.48. PMID 27211790.
- ↑ Lysén M, Thorhagen M, Brytting M, Hjertqvist M, Andersson Y, Hedlund KO (2009). "Genetic diversity among food-borne and waterborne norovirus strains causing outbreaks in Sweden". J Clin Microbiol. 47 (8): 2411–8. doi:10.1128/JCM.02168-08. PMC 2725682. PMID 19494060.
- ↑ Havelaar AH, Kirk MD, Torgerson PR, Gibb HJ, Hald T, Lake RJ; et al. (2015). "World Health Organization Global Estimates and Regional Comparisons of the Burden of Foodborne Disease in 2010". PLoS Med. 12 (12): e1001923. doi:10.1371/journal.pmed.1001923. PMC 4668832. PMID 26633896.
- ↑ Le Guyader FS, Atmar RL, Le Pendu J (2012). "Transmission of viruses through shellfish: when specific ligands come into play". Curr Opin Virol. 2 (1): 103–10. doi:10.1016/j.coviro.2011.10.029. PMC 3839110. PMID 22440973.
- ↑ Verhoef L, Kouyos RD, Vennema H, Kroneman A, Siebenga J, van Pelt W; et al. (2011). "An integrated approach to identifying international foodborne norovirus outbreaks". Emerg Infect Dis. 17 (3): 412–8. doi:10.3201/eid1703.100979. PMC 3166008. PMID 21392431.
- ↑ Ahmed SM, Hall AJ, Robinson AE, Verhoef L, Premkumar P, Parashar UD; et al. (2014). "Global prevalence of norovirus in cases of gastroenteritis: a systematic review and meta-analysis". Lancet Infect Dis. 14 (8): 725–730. doi:10.1016/S1473-3099(14)70767-4. PMID 24981041.
- ↑ Debbink K, Lindesmith LC, Ferris MT, Swanstrom J, Beltramello M, Corti D; et al. (2014). "Within-host evolution results in antigenically distinct GII.4 noroviruses". J Virol. 88 (13): 7244–55. doi:10.1128/JVI.00203-14. PMC 4054459. PMID 24648459.