DETECTION OF HUMAN ADENOVIRUSES IN COASTAL WATERS OF SOUTHERN CALIFORNIA

More than 100 different types of viruses are found in human waste and are potentially transmitted by water. These viruses are more resistant to environmental conditions and sewage treatment processes than many of the sewage related bacteria. Therefore, the use of bacterial indicators to predict the virological quality of water is questionable. To understand the public health risk due to viral contamination, water samples were taken from 12 public beaches adjacent to freshwater inputs from Malibu to the Mexican boarder between February 8th to March 1st 1999. An additional sample was also taken from the Huntington Beach Pier on September 1, 1999 when the beach was reopened after closure for nearly two months due to an elevated level of bacterial indicators. For human adenovirus detection, water samples were concentrated by a Vortex Flow Filtration (VFF) concentrator from 20 liter to 40 to 60 ml. The viral nucleic acids were either extracted directly from the VFF concentrate using a silica bead adsorption method or were extracted using the same method after the sample was further concentrated by ultracentrifugation. A nested PCR protocol was used to amplify adenovirus using primers specific for the hexon. Samples were also analyzed for the presence of coliphage by a top agar overlay method using E.coli ATTCC 15597 as a host. The salinity at sampling sites ranged from 9 to 34 parts per thousand. Coliphages were detected at all sites with the concentrations ranging from 5.3 to over 3300 PFU per liter of water. The highest coliphage concentration was found at the mouth of the Tijuana River. Most of the other sites had one to two orders of magnitude less coliphage counts. Viable plate counts ranged from 5.6 × 105 to 2.45 × 108 per liter with the highest counts observed at the mouth of major rivers, including the Los Angeles, San Diego, and Tijuana River. The number of viable heterotropic bacteria plate counts correlated with the abundance of coliphage (R2=0.88), except for the Tijuana River water sample where extremely high counts of coliphage were detected. Five of 13 samples tested PCR positive for adenovirus, including the mouths of the Los Angeles, San Gabriel, Santa Ana, Tijuana rivers and the Huntington Beach Pier. The number of minimal viral genome ranged from 90.6 to 5.6 × 103/L. Interestingly, the highest concentration of adenovirus was detected at the Huntington Beach Pier, while the lowest was found at the mouth of the Tijuana River. The results of this study indicated the presence of a human pathogenic virus in beach waters of Southern California. Therefore, there is a potential health risk associated with contacting polluted waters during recreational activity. The results of this study also call for a re-evaluation of the current coastal water quality standards.