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Epidemiol Infect. 2015 Sep;143(12):2486-93. doi: 10.1017/S0950268814003628. Epub 2015 Jan 8.

A norovirus oyster-related outbreak in a nursing home in France, January 2012.

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Regional Office of the French Institute for Public Health Surveillance (InVS-Cire Pays de la Loire),Nantes,France.
IFREMER, Laboratoire de Microbiologie,Nantes,France.
National Reference Centre for Enteric Viruses,Dijon,France.
Residence Les Collines,Pouzauges,France.


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.


Foodborne infections; Norwalk agent and related viruses; gastroenteritis; infectious disease epidemiology; investigation

[Indexed for MEDLINE]

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