title: Chronic or accidental exposure of oysters to norovirus: is there any difference in contamination?
abstract: Bivalve molluscan shellfish such as oysters may be contaminated by human pathogens. Currently, the primary pathogens associated with shellfish-related outbreaks are noroviruses. This study was conducted to improve understanding of oyster bioaccumulation when oysters were exposed to daily contamination or one accidental contamination event, i.e., different modes of contamination. Oysters were contaminated with two representative strains of norovirus (GI.1 and GII.3) and then analyzed with real-time reverse transcription PCR. Exposure to a repeated virus dose for 9 days (mimicking a growing area subjected to frequent sewage contamination) led to an additive accumulation that was not significantly different from that obtained when the same total dose of virus was added all at once (as may happen after accidental sewage discharge). Similarly, bioaccumulation tests performed with mixed strains revealed additive accumulation of both viruses. Depuration may not be efficient for eliminating viruses; therefore, to prevent contaminated shellfish from being put onto the market, continuous sanitary monitoring must be considered. All climatic events or sewage failures occurring in production areas must be recorded, because repeated low-dose exposure or abrupt events may lead to similar levels of accumulation. This study contributes to an understanding of norovirus accumulation in oysters and provides suggestions for risk management strategies.
authors: Laboratoire de Microbiologie, Institut Français de Recherche pour l'Exploitation de la Mer, BP 21105, 44311 Nantes cedex 03, France.
authors: Iole
authors: I
authors: Ventrone
authors: Julien
authors: J
authors: Schaeffer
authors: Joanna
authors: J
authors: Ollivier
authors: Sylvain
authors: S
authors: Parnaudeau
authors: Tiziana
authors: T
authors: Pepe
authors: Jacques
authors: J
authors: Le Pendu
authors: Françoise S
authors: FS
authors: Le Guyader
mesh_terms: D000818:Animals; D003257:Consumer Product Safety; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006801:Humans; D029322:Norovirus / Q000302:isolation & purification* / Q000472:pathogenicity; D010125:Ostreidae / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012722:Sewage / Q000821:virology; D012758:Shellfish / Q000821:virology*; D014871:Water Microbiology
chemical_list: D012722:Sewage