Waterborne virus diseases.

Water is only one route by which enteric viruses spread in a population. Other routes, such as the direct person to person contact, are in many circumstances more important. With the introduction of sanitary living conditions the water route becomes of increasing importance. In these conditions populations are not exposed at an early age to virus infections and so do not acquire the immunity that would offer them protection later in life, with the result that a chance exposure to a virus through water or food may be much more serious than it would be to someone who had acquired early immunity. Consequently the detection of enteric and other viruses in water and the epidemiology of the diseases are crucial.