Abstract
Procedures for the detection of cytopathic enteroviruses in the water cycle were assessed. A method was developed and applied to a wide range of field samples. It depended upon concentration of viruses by adsorption to epoxy-bound fibre-glass filter tubes with subsequent elution of viruses with beef extract solution. Viruses were further concentrated by organic flocculation and infectivity assayed by a suspended cell plaque method using BGM cells. Cytopathic enteroviruses, limited to serotypes of polioviruses, coxsackie group B viruses and echoviruses, were isolated from treated and untreated potable waters, surface waters, raw sewages and wastewater effluents. The relationships of physicochemical and bacteriological pollutants to viral contamination were examined and indicated that as levels of bacteria rose the likelihood of viruses also being present increased. However, the correlation was poor because viruses were found in the absence of indicator bacteria and conversely. The virological quality of the Severn and Trent river catchments revealed that two tributaries, the river Stour and the river Tame, were the major sources of viral pollution in each catchment respectively. Storage of river waters, destined for further treatment as drinking water, for at least fifty days resulted in significant reductions of the numbers of viruses. Similarly, long-term lagooning of wastewater effluents resulted in a substantial decline in virus titres. The value of other forms of wastewater treatment, sedimentation, activated sludge, percolating filtration and sand filtration, effected unpredictable reductions of virus numbers. The case for surveillance of virus levels in the water cycle is stressed.