Possible relation between a winter epidemic of acute gastroenteritis in France and viral contamination of shellfish

Several outbreaks of gastroenteritis related to the consumption of shellfis h (frequently eaten raw) have been reported in different parts of the world . In Europe, human calicivirus infections may have been involved in winter outbreaks in recent years, although there is little evidence confirming suc h viral contamination in shellfish. This study presents the first results o f a field survey on viral contamination in two shellfish harvesting areas a long the French Mediterranean coast. The first, consisting mainly of oyster beds, was classified in category A, as determined by fecal coliform counts in shellfish (European Community Directive 91/492), and the second, a muss el bed, was classified in category C. Shellfish samples were collected mont hly between August, 1995 and April, 1997, and RT-PCR was used to detect vir uses known to be involved in outbreaks of gastroenteritis: enterovirus, hum an calicivirus? rotavirus, and astrovirus. Contamination by fecal coliforms was evaluated in the same samples. Virological results in shellfish were c orrelated with data on the incidence of epidemics of gastroenteritis in the coastal population obtained from a French survey. A relationship was obser ved between virological results and epidemiological data. For the 2 years w hen the incidence rate of gastroenteritis was maximal in winter, the mussel bed was always contaminated by the four types of viruses screened. Similar results were observed for oyster beds during the second winter; whereas, t wo samples were highly contaminated during the first winter, and a third sh owed low contamination (only rotavirus). These results suggest that an epid emic of gastroenteritis in the human population contributed to viral contam ination of the marine environment through discharge of waste water.