ABSTRACT
The relative efficacy of the card test in the diagnosis of human brucellosis was evaluated by comparison with four other tests: the standard tube agglutination test, centrifugation agglutination test, 2-mercaptoethanol degradation technique, and 2-mercaptoethanol centrifugation agglutination test. A total of 1,701 serum specimens from persons with various degrees of potential exposure to brucella organisms or cross-reactive antigens were used in this study. In comparison with standard tube agglutination results, the card test had a sensitivity of 95.3% and a specificity of 84.1%. The card-test antigen was nonreactive with serum specimens from tularemia patients and cholera vaccinees. Our data indicated that this test measures both immunoglobulin G and immunoglobulin M agglutinins. The value of the card test in the presumptive serological diagnosis of clinical brucellosis in humans appears to be low; however, the card test may be of value in serological surveys to delineate high-risk populations.
