A Survey by the sewage swab method of latent enteric infection in an urban area

(With 4 Figures in the Text) A simple technique for the location of enteric carriers in towns by means of serial sewage examinations has been described in two earlier papers by Moore (1948, 1950). The principle underlying this method is essentially that some form of continuous sampling of the sewage passing along a particular sewer should be a more sensitive index of the passage of enteric organisms than the examination of bulk samples of sewage, taken from the sewer at times which could not be related in advance to the personal habits of a hypothetical excreter of enteric In both of the papers cited, reference was made to investigations carried out at Sidmouth during the past few years. This work was undertaken mainly to develop methods for the location of enteric carriers, and the techniques which proved satisfactory in Sidmouth were then successfully applied to the solution of an unexplained paratyphoid outbreak at another place. Our investigations were also relevant to local problems, however, as many sporadic cases of both typhoid and paratyphoid fever have been notified from Sidmouth during the past 15 years and its record in this respect has been far worse than that of any other town of similar size along the South Devon coast. It was hoped that our investigations might throw some light on these infections, the majority of which had not been satisfactorily explained by the usual methods of epidemiological inquiry. Un- fortunately, a long enforced leave of absence of one of us has curtailed the scope of the investigations originally planned, and the survey of Sidmouth has in consequence not been completed to our satisfaction. Such results as we have obtained are here presented, and various problems posed by the survey are discussed. Some suggestions are also made on the possible application of the methods we have used to various epidemiological problems.