title: A norovirus oyster-related outbreak in a nursing home in France, January 2012.
abstract: The presence of norovirus in shellfish is a public health concern in Europe. Here, we report the results of an investigation into a norovirus gastroenteritis outbreak following a festive lunch which affected 84 (57%) residents and staff members of a nursing home in January 2012 in France. Individuals who had eaten oysters had a significantly higher risk of developing symptoms in the following 2·5 days than those who had not, the risk increasing with the amount eaten [relative risk 2·2 (1·0-4·6) and 3·3 (1·6-6·6) for 3-4 and 5-12 oysters, respectively]. In healthy individuals during those days, 29 (32%) subsequently became ill, most of whom were staff members performing activities in close contact with residents. Genogroup II noroviruses were detected in faecal samples, in a sample of uneaten oysters and in oysters from the production area. Identifying a norovirus's infectious dose may facilitate the health-related management of contaminated shellfish.
authors.affiliation: Regional Office of the French Institute for Public Health Surveillance (InVS-Cire Pays de la Loire),Nantes,France.
authors.forename: P
authors.initials: P
authors.lastname: Loury
authors.affiliation: IFREMER, Laboratoire de Microbiologie,Nantes,France.
authors.forename: F S
authors.initials: FS
authors.lastname: Le Guyader
authors.affiliation: IFREMER, Laboratoire de Microbiologie,Nantes,France.
authors.forename: J C
authors.initials: JC
authors.lastname: Le Saux
authors.affiliation: National Reference Centre for Enteric Viruses,Dijon,France.
authors.forename: K
authors.initials: K
authors.lastname: Ambert-Balay
authors.affiliation: Residence Les Collines,Pouzauges,France.
authors.forename: P
authors.initials: P
authors.lastname: Parrot
authors.affiliation: Regional Office of the French Institute for Public Health Surveillance (InVS-Cire Pays de la Loire),Nantes,France.
authors.forename: B
authors.initials: B
authors.lastname: Hubert
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D000818:Animals; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000635:transmission; D004196:Disease Outbreaks; D005602:France / Q000453:epidemiology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology; D006282:Health Personnel; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional; D008875:Middle Aged; D029322:Norovirus; D009735:Nursing Homes; D010125:Ostreidae / Q000821:virology*; D012189:Retrospective Studies; D057096:Shellfish Poisoning / Q000453:epidemiology* / Q000821:virology
keywords: Foodborne infections; Norwalk agent and related viruses; gastroenteritis; infectious disease epidemiology; investigation