The health significance of viruses in water

Abstract

There is no question that water may transmit pathogenic viruses. In fact, epidemiological data on the incidence of water-borne viral diseases probably fail to reflect the true extent of the hazard. However, it is equally clear that the technology to produce virologically safe water is available, but often not applied. Viral infections could always be traced to inefficient treatment, break-down of equipment, or secondary pollution in distribution systems. In addition, the efficiency of treatment processes can reliably be assessed by means of microbiological indicator systems. This information should now be used in research on the improvement of water treatment and surveillance systems in terms of cost, efficiency and reliability in order to ensure more safe water for more people throughout the world. The role of water in the overall incidence of microbial diseases and the optimum utilization of financial resources for the benefit of public health in general should be a major consideration in these endeavours. Monitoring procedures must include operational and chemical control as well as practical microbiological assays to detect treatment deficiencies. It should be possible to perform the microbiological tests economically at high frequency in conventional laboratories, and reliable results should be available in a short time. Evidence has been presented that presently available virological tests, which do not meet these requirements, may be eliminated from routine monitoring. However, the optimization of water treatment and surveillance for the many different uses and users of water, requires more information on the incidence and behaviour of viruses in water, the relation of pathogenic viruses to indicators, the virucidal efficiency and mechanism of action of treatment processes, and the epidemiology of waterborne viral diseases. Success in these efforts will heavily depend upon a multi-disciplinary approach and close co-operation among fields of expertise such as engineering, microbiology, chemistry, public health, epidemiology, economics, statistics and education.