The diagnosis of enteric fever currently depends upon the isolation of Salmonella from a patient, most commonly by blood culture. This facility is not available in many areas where the disease is endemic. Serodiagnosis depends upon the 100-year-old Widal test, and other serological diagnostic tools have limitations because of their low sensitivity and/or specificity. The most promising recently...

The diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA) is a new and simple method for quantitation of antibodies, based on the ability of antibodies to diffuse from wells in gel and adsorb to antigen which is bound to a polystyrene surface. The antigen-antibody reaction is visualized with a color reaction caused by horseradish peroxidase-conjugated class-specific anti-immunoglobins....