Evaluation of a single Widal test in the diagnosis of enteric fever.

The usefulness of a single Widal test was evaluated in an endemic area. This test was done on 62 bacteriologically proven enteric fever cases, 69 non-enteric fever cases and healthy individuals. Using an 0 antibody cut-off of greater than or equal to 1:20, the Widal tube agglutination test yielded a sensitivity of 61% and a specificity of 88%. At a pre-test probability of around 50%, the positive predictive value was 83% and the negative predictive value was 72%. A 4% prevalence of 0 antibodies was noted in the healthy population.