Les Toxi-Infections Alimentaires Collectives (TIAC) virales associées à la consommation d'huîtres en France, hiver 2000-2001

During the winter 2000/2001, several outbreaks associated with the consumption of shellfish were declared in France. Following these events, a close cooperation was organized between administrations and laboratories (DGAL, DPMA, InVS, AFSSA, Ifremer, CHU-Dijon and CNC) to gather competences and to manage the situation. This report synthesizes the information collected during these outbreaks. From the outset, the epidemiologic investigations directed the research towards viral contamination and shellfish as contamination source. Several outbreaks were investigated. Oysters and stools samples from ill patients were analysed by RT-PCR for viruses (enterovirus, rotavirus, norovirus and astrovirus). The genic amplification was done by using the same primers in shellfish and stool samples. In the positive samples, all the detected viruses belonged to the family of norovirus (genogroupe 1 or II). The same strain was found in the oysters and in the stool for two outbreaks. For other outbreaks, no virus was detected in any sample. In the remaining cases, the virus was present either in the stools or in the shellfish or in both, but the strains were not the same. The synthesis of the collected data (epidemiologic, virological analyses, environmental) points out the importance of the viral risk in winter when the following phenomena - strong rainfall and epidemics of gastro-enteritises in the population- are concomitant. These two phenomena were exceptional and simultaneous during the winter 2000/2001. This information can be used for the development of a waming system to prevent this risk and protect the consumer.