title: Infectivity of GI and GII noroviruses established from oyster related outbreaks.
abstract: Noroviruses (NoVs) are the major cause of acute epidemic gastroenteritis in industrialized countries. Outbreak strains are predominantly genogroup II (GII) NoV, but genogroup I (GI) strains are regularly found in oyster related outbreaks. The prototype Norwalk virus (GI), has been shown to have high infectivity in a human challenge study. Whether other NoVs are equally infectious via natural exposure remains to be established. Human susceptibility to NoV is partly determined by the secretor status (Se+/-). Data from five published oyster related outbreaks were analyzed in a Bayesian framework. Infectivity estimates where high and consistent with NV(GI) infectivity, for both GII and GI strains. The median and CI95 probability of infection and illness, in Se+ subjects, associated with exposure to a mean of one single NoV genome copy were around 0.29[0.015-0.61] for GI and 0.4[0.04-0.61] for GII, and for illness 0.13[0.007-0.39] for GI and 0.18[0.017-0.42] for GII. Se- subjects were strongly protected against infection. The high infectivity estimates for Norwalk virus GI and GII, makes NoVs critical target for food safety regulations.
authors.affiliation: Anses, Maisons-Alfort, France. anne.thebault@anses.fr
authors.forename: Anne
authors.initials: A
authors.lastname: Thebault
authors.forename: Peter F M
authors.initials: PF
authors.lastname: Teunis
authors.forename: Jacques
authors.initials: J
authors.lastname: Le Pendu
authors.forename: Françoise S
authors.initials: FS
authors.lastname: Le Guyader
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Denis
mesh_terms: D000818:Animals; D017250:Caliciviridae Infections / Q000453:epidemiology / Q000821:virology*; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005506:Food Contamination; D005602:France / Q000453:epidemiology; D005838:Genotype; D006801:Humans; D008954:Models, Biological; D029322:Norovirus / Q000235:genetics / Q000472:pathogenicity*; D010125:Ostreidae / Q000821:virology*