title: A review of known and hypothetical transmission routes for noroviruses.
abstract: Human noroviruses (NoVs) are considered a worldwide leading cause of acute non-bacterial gastroenteritis. Due to a combination of prolonged shedding of high virus levels in feces, virus particle shedding during asymptomatic infections, and a high environmental persistence, NoVs are easily transmitted pathogens. Norovirus (NoV) outbreaks have often been reported and tend to affect a lot of people. NoV is spread via feces and vomit, but this NoV spread can occur through several transmission routes. While person-to-person transmission is without a doubt the dominant transmission route, human infective NoV outbreaks are often initiated by contaminated food or water. Zoonotic transmission of NoV has been investigated, but has thus far not been demonstrated. The presented review aims to give an overview of these NoV transmission routes. Regarding NoV person-to-person transmission, the NoV GII.4 genotype is discussed in the current review as it has been very successful for several decades but reasons for its success have only recently been suggested. Both pre-harvest and post-harvest contamination of food products can lead to NoV food borne illness. Pre-harvest contamination of food products mainly occurs via contact with polluted irrigation water in case of fresh produce or with contaminated harvesting water in case of bivalve molluscan shellfish. On the other hand, an infected food handler is considered as a major cause of post-harvest contamination of food products. Both transmission routes are reviewed by a summary of described NoV food borne outbreaks between 2000 and 2010. A third NoV transmission route occurs via water and the spread of NoV via river water, ground water, and surface water is reviewed. Finally, although zoonotic transmission remains hypothetical, a summary on the bovine and porcine NoV presence observed in animals is given and the presence of human infective NoV in animals is discussed.
authors: Department of Infectious and Parasitic diseases, Virology and Viral diseases, Faculty of Veterinary Medicine, University of Liège, Boulevard du Colonster 20, 4000, Liège, Belgium.
authors: Elisabeth
authors: E
authors: Mathijs
authors: Ambroos
authors: A
authors: Stals
authors: Leen
authors: L
authors: Baert
authors: Nadine
authors: N
authors: Botteldoorn
authors: Sarah
authors: S
authors: Denayer
authors: Axel
authors: A
authors: Mauroy
authors: Alexandra
authors: A
authors: Scipioni
authors: Georges
authors: G
authors: Daube
authors: Katelijne
authors: K
authors: Dierick
authors: Lieve
authors: L
authors: Herman
authors: Els
authors: E
authors: Van Coillie
authors: Mieke
authors: M
authors: Uyttendaele
authors: Etienne
authors: E
authors: Thiry
mesh_terms: D000818:Animals; D017250:Caliciviridae Infections / Q000453:epidemiology / Q000209:etiology / Q000635:transmission* / Q000821:virology; D004196:Disease Outbreaks; D005511:Food Handling; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000821:virology*; D005759:Gastroenteritis / Q000821:virology*; D005838:Genotype; D006801:Humans; D029322:Norovirus / Q000235:genetics; D014871:Water Microbiology; D015047:Zoonoses