Epidemiologic and Molecular Trends of “Norwalk‐like Viruses” Associated with Outbreaks of Gastroenteritis in the United States

Abstract

Between July 1997 and June 2000, fecal specimens from 284 outbreaks of nonbacterial gastroenteritis were submitted to the Centers for Disease Control and Prevention for testing for "Norwalk-like viruses" (NLVs). Specimens were examined by reverse-transcription polymerase chain reaction and direct electron microscopy for the presence of NLVs. Adequate descriptive data were available from 233 of the outbreaks, and, of these, 217 (93%) were positive for NLVs. Restaurants and events with catered food were the most common settings, and contaminated food was the most common mode of transmission. Genogroup II (GII) strains were the predominant type (73%), with genogroup I strains causing 26% of all NLV-positive outbreaks. Certain GII clusters (GII/1,4,j) were more commonly associated with outbreaks in nursing home settings than with outbreaks in other settings. Strain diversity was great: one potential new sequence cluster was implicated in multiple outbreaks, and strains belonging to a tentative new genogroup were identified.

Genetic diversity of noroviruses in Brazil

“…Protocols using primers that amplify regions A and B have been widely used for viral detection because this is a highly conserved region (Ando et al 1995, Jiang et al 1999, Fankhauser et al 2002. Still, regions C and D, which comprise different partial sequences of the gene encoding for VP1 protein, are recommended for the characterization of different genotypes (Mattison et al 2009).…”

“…It is transmitted faeco-orally by ingesting contaminated food and water. However, infection can also occur through person-person contact, fomites or by aerosols produced during vomiting (Fankhauser et al 2002, Lopman et al 2002, Marks et al 2003. These infections are often reported in nursing homes, kindergartens, hospitals, schools, cruise ships, restaurants, military installations and resorts (Leuenberger et al 2007, Podewils et al 2007, Rizzo et al 2007, Verhoef et al 2008.…”

“…Since the 1990s, the development of amplification protocols for different genomic regions, denominated regions A and B (ORF-1), C, D and E (ORF-2), has resulted in a NoV diagnostic breakthrough in several countries (Ando et al 1995, Green et al 1995, Noel et al 1997, Fankhauser et al 2002, Kojima et al 2002, Vennema et al 2002, Vinjé et al 2004. A global electronic network surveillance of NoV, Noronet (noronet.nl), was established following an agreement between three networks involved in molecular surveillance of NoV: the Australian and New Zealand NoV Surveillance Network, the Foodborne Viruses in Europe Network and the CaliciNet in USA.…”

Porcine enteric caliciviruses: Genetic and antigenic relatedness to human caliciviruses, diagnosis and epidemiology

“…In 2002, Norwalk and Norwalk-like viruses were assigned to the genus Norovirus [2]. Since the discovery of Norwalk virus, NoVs have emerged as the most common pathogen causing food-and water-borne viral gastroenteritis in humans including both outbreaks and sporadic cases worldwide [7][8][9][10]. The human NoVs have been listed as class B biological pathogens by the National Institutes of Health/Biodefense Program.…”

Asymptomatic and Symptomatic Excretion of Noroviruses during a Hospital Outbreak of Gastroenteritis

“…The genomic diversity of noroviruses includes two genogroups (I and II) (2,18) and a number of genotypes (8), on which formal agreement has yet to be reached. Representatives of genogroup I genotypes include GI-1 (Norwalk/1968/ US), GI-2 (Southampton/1991/UK), GI-3 (Desert Shield/ 1990/SA), and GI-4 (Valetta/1995/MA), while genogroup II genotypes include GII-1 (Hawaii/1971/US), GII-2 (Melksham/ 1994/UK), GII-3 (Mexico/1989/MX), and GII-4 (Grimsby/ 1995/UK).…”