PCR detection of pathogenic viruses in southern California urban rivers

Aims: To investigate human viral contamination in urban rivers and its impact on coastal waters of southern California, USA. Methods and Results: Three types of human viruses (adeno, entero and hepatitis A) were detected using nested- and RT-PCR from 11 rivers and creeks. Faecal indicator bacteria as well as somatic and F-specific coliphage were also tested. Approximately 50% of the sites were positive for human adenoviruses. However, there was no clear relationship between detection of human viruses and the concentration of indicator bacteria and coliphage. Both faecal indicator bacteria and human viral input at beaches near river mouths were associated with storm events. The first storm of the wet season seemed to have the greatest impact on the quality of coastal water than following storm events. Conclusions: This study provides the first direct evidence that human viruses are prevalent in southern California urban rivers. Urban run-off impacts coastal water quality most significantly during the storm season. Significance and Impact of the Study: To protect human health during water recreational activities, it is necessary to develop effective strategies to manage urban run-off during storm events.