Human enteric viruses in Australian bivalve molluscan shellfish

Human enteric viruses in Australian bivalve molluscan shellfish Outbreaks of gastroenteritis, caused by norovirus-contaminated shellfish, occur worldwide and have occasionally been linked to shellfish of Australian origin. There is, however, a paucity of data on norovirus occurrence in Australian shellfish. This, together with outbreaks and the impending introduction of international policies for norovirus in shellfish, provided impetus to investigate the prevalence of norovirus in Australian oysters. Norovirus and E. coli occurrence in Australian oysters from six growing areas in the three main oyster producing states (two areas per state) was assessed. Oysters were sampled on four occasions, through four seasons, during 2010 and 2011 and norovirus GI, GII and E. coli prevalence determined. Norovirus GII was detected in two of 120 (1.7 %) samples. Norovirus GI was not detected. Five samples (4.2 %) exceeded the regulatory level of 230 E. coli per 100g. No human illnesses due to norovirus-contaminated oysters were reported during the survey period. In a spatial and temporal study of norovirus and E. coli in oysters after a raw sewage overflow into a river estuary, no Hepatitis A virus was detected. The results of sequence analysis of the virus strains detected in the norovirus-positive oyster samples will be presented and their significance discussed.