Agglutination tests in the diagnosis of enteric fever in the inoculated

Abstract

1. Early blood culture is the best method of laboratory diagnosis in the inoculated case of enteric fever, but agglutination tests may give useful information.2. In inoculated cases of enteric fever O and Vi agglutinins may be absent or present only at low titres. Steadily rising titres are not the rule and the titres more often fluctuate.3. Complete agglutination at titres over 1: 80 for TO, over 1: 40 for AO, or over 1: 10 for Vi is suggestive but not diagnostic of an active infection.4. Non-specific stimulation of the O and Vi agglutinins in the inoculated affects mainly the lower range of titres which are probably of little diagnostic significance.5. Previous inoculations increase the proportion of people with residual O agglutinins within 6 months of the last inoculation but do not affect the Vi agglutinins.6. Vi agglutinins may be present in normal inoculated persons who are not carriers.