Diagnosis of typhoid fever by the detection of anti-LPS & anti-flagellin antibodies by ELISA.

In a developing country like ours where typhoid fever is endemic and there are very few microbiology laboratories to provide diagnosis by culture, a search for non culture techniques for rapid and reliable diagnosis continues. The Widal test has a low sensitivity. We have attempted to adapt the well established enzyme linked immunosorbent assay (ELISA) technique to provide a serological test of better sensitivity and specificity. The ELISA described here to detect anti-LPS antibodies was found to have a sensitivity of 89.4 per cent and a specificity of 94.9 per cent. The sensitivity for the antiflagellin ELISA was 68.1 per cent and specificity was 97.4 per cent. The likelihood ratio was 17.5 for anti-LPS ELISA and 26.2 for the anti-flagellin ELISA. Considering the positivity of either one ELISA as diagnostic, the sensitivity was 93.6 per cent and specificity was 94.9 per cent.