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Aims: To investigate Norovirus (NoV) contamination of mussels, clams and oysters harvested in two class B harvesting areas of the delta of the Po river, to choose a species as an indicator. Methods and Results: Environmental parameters (temperature and salinity) and hydrometric levels of the tributary river were measured. Seventy shellfish samples (35 samples per area) were examined for Escherichia coli and NoV (GI and GII). NoV contamination was found in 51·4% of samples, of which, 2·9% contained only NoV GI, 14·3% only NoV GII, while the majority of the samples (34·3%) contained both genogroups. Most of the positive results (90·0%) were obtained in the period between November 2008 and April 2009. Conclusions: No significant differences were found between the results from the two harvesting areas and the three shellfish species. However, on the basis of the average C t values, the recovery rate (from 0·46 to 1·15%) and the distribution of positive results in the samplings, mussels seem to be a suitable indicator species to monitor viral contamination in these areas. Significance and Impact of the Study: The data allow the optimization of monitoring plans to improve the prevention strategies in terms of money and time, by the intensification of controls in the cold season and the use of one species as indicator.

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During recent decades, ornamental fish have proven to be one of the fastest growing categories of pets in Europe. In this framework, we evaluated both the potential pathogenic and zoonotic risks caused by 53 Vibrio cholerae non-O1/non-O139 and a Vibrio mimicus strain isolated from ornamental fish species mostly originating from South-East Asia countries between 2000 and 2015 in Italy. All the strains were firstly identified at species level by biochemical, phylogenetic and mass spectrometry (matrix-assisted laser desorption ionization time of flight) methods, and then studied to reveal the presence of the main virulence and colonization-associated factors, as ctxA, ace, zot, stn/sto, toxR, rtxA, hlyA and tcpA by multiplex and single endpoint PCR assays. Findings showed that 21 of 54 strains harboured at least one virulence factor with a predominance for the toxR , rtxA and hlyAET genotype. Interestingly, the V. mimicus strain harboured the colonization factor and the CTX prophage receptor, tcpA, indicating the ability to capture and integrate it in its genome increasing its pathogenicity. Although these enterotoxins can sporadically cause gastroenteritis, the results highlight their probable involvement in causing severe implications for public health, suggesting the need for an European microbiological monitoring.