DETECTION OF VIRUSES IN COASTAL AND RIVER WATER-SYSTEMS IN SYDNEY, AUSTRALIA

Two prospective studies on the occurrence of human viruses in samples of coastal & river origin have been undertaken since September 1989. Viruses were detected using concentration methods & cell culture techniques. Water samples (100L) were reduced to 1L using hollow fibre ultrafiltration and then treated with PEG. Sewage and sediment samples were treated with PEG only. Over a two year period, viruses were detected in 24/202 (12%) of water samples and 29/60 effluents from the river system. Coastal waters have been contaminated by cliff edge discharge of sewage for at least the 1 ast 70 years. Recently, deepwater ocean outfalls have been installed to discharge effluent some 3 km away from the coast. Prior to the installation of deepwater ocean outfalls viruses were detected in 28% of water samples compared to 9% post installation. In sediment samples viruses were isolated in 87/260 (34%) samples, the discharge via the new outfalls having no effect on the isolation rate. The data points to long term survival of viruses in sediments and/or contamination from other sources such as storm water discharge: 10-25% of storm water drains were also found to be positive for viruses. The viruses isolated were enteroviruses, adenoviruses & reoviruses. Although viruses were consistently isolated with some seasonal trends, comparisons between the detection of viruses in clinical and environmental samples over this two year period were inconclusive.