Adenovirus as swimming pool virological quality indicator

Several authors reported that half of recreational water-related outbreaks events occurred in swimming pools due by a variety of microorganisms, which may be introduced in a number of ways. In many cases, the risk of infection has been linked to faecal contamination of the water originated by bathers or input water while non-faecal human shedding (e.g. from vomit, mucus, saliva or skin) is a potential source of pathogenic organisms. Most of them are enteric viruses such as rotavirus, norovirus, adenovirus, astrovirus, enterovirus and hepatitis A virus. For this aim, a quality index, demonstrating the viral presence and predictive of health effects in swimming pool would be useful. At the moment the suggested recreational water quality standards, are bacterial indicators, such as intestinal enterococci and Escherichia coli, related to sewage contamination, and somatic coliphages that are similar to pathogenic enteric viruses concerning environmental attenuation. However it’s well known the lack of a consistent correlation between these indicator organisms and viral pathogens. Among waterborne viruses, special attention should be given to human adenoviruses (HAdV) because they have a number of features that justify their indication as a virologic marker for the quality of water. HAdV are members of the genus Mastadenovirus in the Adenoviridae family, which comprises 52 serotypes classified into 7 species (A–G). The wide presence in environmental waters and its resistance to disinfection treatment justified its utilizing as indicator. During several monitoring campaigns of our Laboratory, HAdV were successfully detected after concentration of water samples by ultrafiltration and analysis using biomolecular tests (PCR and quantitative PCR) in seawaters with a mean positive samples of 20%, rivers (80%), sewage systems (100%) and treated waters (40%). The average viral concentration ranged from a maximum of 8.79 Log Genomic Copies/l of sewage samples to 3.67 Log GC/l for seawaters, 3.53 Log GC/l for river waters and 2.3 Log GC/l for treated ones. The same samples were parallel analized by ISO methods for suggested quality standard cited above (E. coli, intestinal enterococci and somatic coliphages) and quantitative data were often statistical not correlated with HAdV, even in some viral positive seawater and treated waters the values are very low under directive limit. Our data are in compliance with other published studies regarding positive viral samples frequency and quantity, confirming the possible role of HAdV as indicators for water quality. They could be particularly important in swiming pools considering also their resistance to chlorine end their involvements in outbreaks occurring