[Source: Epidemics, full page: (LINK). Abstract, edited.]
Epidemics - Available online 4 January 2013
Infectivity of GI and GII noroviruses established from oyster related outbreaks
Anne Thebaulta Peter F.M. Teunisb, c, Jacques Le Pendud, e, f, Françoise. S. Le Guyaderg, Jean-Baptiste Denish
a Anses, Maisons-Alfort, France; b National Institute of Public Health and the Environment, Bilthoven, The Netherlands; c Rollins School of Public Health, Atlanta, Georgia, USA; d INSERM, Nantes, France; e Univ Nantes, Nantes, France; f CNRS, Nantes, France; g IFREMER, Nantes, France; h INRA, Jouy-en-Josas, France
Corresponding author at: UMAMSA, ANSES, 27-31 avenue du général Leclerc BP 19, 94701 Maisons-Alfort, France. Tel.: +331 49 77 38 65; fax: +331 49 77 38 65.
Received 20 July 2012 - Revised 11 December 2012 - Accepted 15 December 2012 - Available online 4 January 2013
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.
► From five oyster related outbreaks data, infectivity of Norovirus was evaluated ► Bayesian analysis was done conditionally from the ingested dose (genome copies) ► Infectivity for secretor positive (Se+) and negative (Se-) individuals is different ► Difference of infectivity between genogroups (GI and GII) is not detected ► High infectivity estimates was confirmed for NoV GI and GII in Se+ individuals.
Norovirus; Shellfish; Bayesian Analysis; Dose-Response Relationship; Fucosyltransferases