A new type of immunoassay (enzyme-linked immunosorbent assay, ELISA) has been used for the detection of antibodies against Salmonella 0 antigens. The results show that ELISA is specific and highly sensitive. When compared with the Widal reaction, passive hemagglutination, and quantitative precipitation, ELISA was shown to be more sensitive. In addition, immunoglobulin G and immunoglobulin M ant...