[Coliphages, viral indicators of contamination].

This paper illustrates the importance of coliphages, which are specific bacteriophages for Escherichia coli strains, as viral indicators, and suggests the usefulness of a routine coliphage search in the detection of viral contamination. The samples studied consisted of 57 surface water, (46 of sea water and 11 of river water), 2 of mud taken from biological treatment plants and 3 samples of sludge. The results revealed that coliphages can be considered valid indicators of viral contamination as they show a good response to the general standards established for indicators. In particular: they are found in sludge (both untreated and treated) and in surface water (both river and sea) in higher concentrations than those of enterovirus; they show greater resistance than bacterial indicators to disinfection as, in different experimental conditions, the drop in the level does not exceed orders of magnitude they are relatively simple to identify, and are easily quantifiable by means of the MPN method, with the result that they can be used for the management of water resources. As regards the possible use of coliphages for the control of the necessary qualitative requisites of sea water for bathing, the relation with fecal coli enables us to make an assessment of coliphages corresponding to 100 fecal coli/100 ml. This levels is equivalent to 0.95 so that a suitable guide line for water for bathing purposes could for example be established at 10 coliphages/1. Although coliphages may be considered good indicators of viral contamination this clearly does not mean that they can replace classic bacterial indicators but rather, that they can provide useful additional information, particularly in those cases where a rapid drop in bacterial content may conceal high risk health and hygiene conditions.