Diagnosis of typhoid fever by Dot enzyme immunoassay in an endemic region.

OBJECTIVE: To compare the results of Dot Enzyme Immunoassay (EIA) and concomitantly performed blood culture for the diagnosis of typhoid fever. METHODS: The results of Dot Enzyme Immunoassay (EIA) of patients who also had blood cultures/bone marrow culture performed at the same time were analyzed. The period of study spans between April 1997-September 1997. RESULTS: A total of 1760 Dot Enzyme Immunoassays were performed from April 1997 to September 1997. Of these, only 128 (7.2%) cases had concomitantly performed blood/bone marrow cultures. Therefore, the study was narrowed down to these 128 cases. Sixty-nine cases were culture positive for S. typhi. Of these culture proven cases, IgM antibodies by Dot EIA were positive only in 49 (71%) cases while 20 (28.9%) of culture proven cases remained negative for IgM antibodies. CONCLUSION: Taking blood/bone marrow culture as gold standard, the sensitivity of Dot EIA was found to be 71% while specificity was found to be 43%. The predictive value of the positive test was found to be 59.7% and that of a negative test was found to be 56.5%.