Viral and bacterial contamination in recreational waters: a case study in the Lisbon bay area

Abstract

To assess the presence of viral pathogens in bathing water samples and to evaluate the interdependency of bacterial indicator counts and viral detection. Bathing water samples of 16 beaches collected along a Portuguese Coastal area were screened for the hepatitis A virus (HAV) and norovirus genogroup I (NVGI) using RT-PCR technique. Bacteriological water quality was also assessed, according to European regulations. HAV and NVGI were detected in 95% and 27% of the water samples, respectively, whereas bacteriological quality was good in all but one sample, according to current water quality regulations. All water samples would be considered of excellent quality according to the most recent European regulations. No relationship between viral detection and regulatory-based bacterial indicators was found. The current results reinforce the importance of increased surveillance for pathogenic viruses in bathing waters.