Comparative evaluation of the enzyme-linked immunosorbent assay in the laboratory diagnosis of brucellosis.

An enzyme-linked immunosorbent assay was adapted to measure total and Brucella abortus-specific immunoglobulin M antibodies. The results were compared with those of conventional serological tests for B. abortus antibody on the sera of a number of normal controls, apparently healthy occupationally exposed workers, and patients with suspected acute brucellosis. Relative to other tests, the B. abortus enzyme-linked immunosorbent assay was found to be both highly sensitive and highly specific. The serological results obtained in occupationally exposed workers indicate a higher "normal range" for this group and therefore a possibility of false-positive results and overdiagnosis. It is therefore important to establish a separate "normal range" for occupationally exposed workers. Investigation of patients with acute brucellosis showed that the enzyme-linked immunosorbent assay for immunoglobulin M was the most sensitive serodiagnostic test and was likely to be of value in the serodiagnosis of acute brucellosis in occupationally exposed workers.