Use of the enzyme-linked immunosorbent assay technique (elisa) for the diagnosis of typhoid fever. I. Standardization of technique.

The sera of 25 patients with bacteriological diagnosis of typhoid fever were analyzed to identify and measure the antibodies to S. typhi somatic antigens using the enzyme-linked immunosorbent assay technique (ELISA). The results were positive in all the serologic tests, with titers varying from 1:600 to 1:2500. Development and standardization of the technique, results of the intra-assay and inter-assay tests and their correlation to Widal's reaction are described in detail.