Detection of typhoid carriers by agglutination tests.

Use of the Vi agglutination test in the detection of chronic carriers of Salmonella typhi (S. typhosa) first was suggested by Felix et al. (1935). Since that time study of the test by many workers has resulted in the accumulation of a voluminous literature which has been reviewed by Klein (1943), Felix (1951), Landy and Lamb (1953), and Spaun (1957). Bhatnagar et al. (1938) recommended the use in Vi agglutination tests of S. typhi Vi 1 of Kauffmann which the latter worker had isolated and found inagglutinable in O and H sera for S. typhi. Since that time the Vi 1 strain has been used almost exclusively in agglutination tests for the detection of typhoid carriers. Desranleau (1943) and Saint-Martin and Desranleau (1951) recommended the use of a slide test using a glycerolated antigen prepared from S. typhi Vi 1. The results obtained by different workers in agglutination tests differed widely in the percentage of carriers detected and in the number of reactions obtained with sera of apparently normal people. Since the Vi 1 strain is quite rough, agglutination tests done with the culture are subject to the difficulties inherent in the use of a rough culture for antigen in agglutination tests. Use of other cultures of S. typhi or of cultures of the Citrobacter (Escherichia freundii) group which contained Vi antigen was rejected either because they reacted with 0 and H agglutinins for S. typhi or because they were insufficiently sensitive to Vi agglutinins. This unsatisfactory condition led Spaun (1951), Bier (1951), Corvazier (1952). LeMinor et al. (1952), and Tomasic et al. (1953) to investigate the sensitization of red cells with various preparations of Vi antigen. The detection of typhoid carriers by Vi hemagglutination tests was investigated by Staack and Spaun (1953) using heated extracts of Vi cultures of S. typhi for sensitization and by Landy and Lamb (1953) using purified Vi antigen for sensitization. Human type 0 red cells were employed in both instances. The number of carriers tested by these investigators was not large, and some control sera, particularly those of vaccinated individuals, gave positive results whereas a small number of known carriers yielded negative tests. The conflicting results obtained in bacterial agglutination tests and hemagglutination tests in the serological investigation of typhoid carriers stimulated the work here reported.