Municipal and agricultural wastewater contain a variety of microorganisms and in particular enteric viruses. For the reuse of this treated wastewater it is important to ensure the efficiency of purification treatments and disinfection practices, that have often been insufficient to lower the viral load below the risk level. For this reason, for the routine analysis of recycled waters, the research into pathogenic viruses (e.g. HAV) and classical bacterial parameters (E. coli, enterococci and Salmonella) has to be associated with specific viral indicators such as somatic coliphages, adenovirus and TTV. The results of environmental monitoring, carried out in a wastewater treatment plant, showed the presence of adenovirus DNA in 100% of collected samples and TTV DNA in 95% (19/20) of raw sewage and in 85% (17/20) of the exit samples, while HAV was detected only in 2 samples over 40 (5%). The quantitative analysis has revealed an average reduction of 2 log for adenovirus and 1.58 log for TTV. The bacterial indicators were reduced by 1.74 log and 1.99 log respectively for E. coli and enterococci, while for somatic coliphages an average reduction of 2.2 log was observed. No significant correlation was shown between these parameters, confirming their inadequacy for the virological risk assessment. However the results of adenovirus confirm it as the best indicator to evaluate the efficacy of wastewater depuration plant in eliminating viruses.

In the aim of studying possible relations between viruses detected in clinical specimens and the ones found in different environmental matrices, in the period May 2004 to April 2005, the collection of faecal samples from gastroenteritis cases and the monthly monitoring of raw and treated wastewater, river water, seawater and mussels were carried out. The viruses considered for environmental monitoring were adenovirus, rotavirus, enterovirus, norovirus, hepatitis A virus (HAV) and Torque teno virus (TTV): they were searched for with PCR and RT-PCR and confirmed by gene sequencing. Faecal coliforms and somatic coliphages' counts were also determined. The surveillance of case detected 45 positive faecal samples out of 255 (17.6%) while 35 of 56 environmental samples (62.5%) resulted positive for at least one of the considered viruses. The detection of the same viral strain in the faeces of gastroenteritis cases and in water was possible for adenovirus and rotavirus, which were also predominant in environmental matrices; thus they could be considered as a reference for risk assessment.