Incidence of foodborne viruses in Crassostrea virginica oysters cultured in the Magdalen Islands region of Eastern Canada.

Consumption of oysters is a frequent cause of viral gastroenteritis worldwide. Discharge from sewage or other wastewater treatment, sewer overflows and discharges from marine vessels are sources of contamination of aquatic environments with human and animal excreta and hence the risk of pathogen bioaccumulation in bivalve molluscs. We tested oysters (Crassostrea virginica) harvested inshore and offshore around the Magdalen Islands (Gulf of St-Lawrence, Eastern Canada) at different months for the presence of human norovirus (HuNoV GI and GII), hepatitis A virus (HAV) and hepatitis E virus (HEV) using the ISO 15216-1:2017 method. Among 52 oyster's sample (13 per time point) we detected HuNoV GI RNA in six and HuNoV GII RNA in one. No sample tested positive for HAV RNA or HEV RNA. The majority of the HuNoV presumptive positive oysters were harvested inshore in November. The screening of oysters for the presence of enteric viruses would contribute to preventing outbreaks of gastroenteritis and should be practiced routinely to monitor the quality of the Gulf of St-Lawrence environment.