Occurrence of enteric viruses in shellfish and relation to climatic-environmental factors

Aims:  To investigate the presence of enteric viruses [hepatitis A (HAV) and norovirus (NoV)] in shellfish harvested from the deltaic area of the Po river in relation to environmental factors. Methods and Results:  Fortnightly sampling of shellfish was carried out in two lagoon areas (category B production areas) and one sea area (category A). Environmental parameters in the lagoon and hydrometric level of the tributary river were monitored throughout the sampling period. Samples (n = 120) were analysed for bacterial (E. coli and Salmonella) and viral (HAV and NoV) contamination; samples from category B areas were analysed before and after purification treatment. All the samples were negative for HAV whereas 10 samples (8·3%), all harvested in the lagoon areas, were positive for NoV. Sequencing identified the strains as genotypes II.4 and II.b. None of the samples was found to be contaminated after depuration. Conclusions:  The monitoring showed a low frequency of NoV presence; viral contamination, detected exclusively in shellfish collected from the deltaic area (category B), could be influenced by the flow of the tributary river. Significance and Impact of the Study:  The data collected are useful for the design of targeted prevention strategies and for the modulation of control plans after meteorological events.