EVALUATION OF THE INDIRECT HEMAGGLUTINATION ASSAY FOR DIAGNOSIS OF ACUTE LEPTOSPIROSIS

Serology plays an important role in the diagnosis of leptospirosis, Fe w laboratories have the resources and expertise to perform the microsc opic agglutination test, There is a need for rapid and simple serologi cal tests which facilitate the early diagnosis of leptospirosis, while antibiotic therapy may be most effective, A commercially available in direct hemagglutination assay (IHA; MRL Diagnostics, Cypress, Calif.) was evaluated with multiple serum specimens from 107 patients being in vestigated for leptospirosis. By using a combination of enzyme-linked immunosorbent assay (ELISA) methods for immunoglobulin M (IgM) and IgG antibodies and the microscopic agglutination test, 54 patients were f ound to have leptospirosis and 53 were found not to have leptospirosis . The sensitivity of IHA for the detection of acute leptospirosis was 100%, the specificity was 94%, the positive predictive value was 95%, and the negative predictive value was 100%. IHA was negative when 13 a ntinuclear antibody-positive sera, 24 serum specimens from patients wi th syphilis, and 16 serum specimens false positive by the Venereal Dis ease Research Laboratory test were tested, IHA was shown to detect bot h IgM and IgG classes of antibodies in human sera, Serum specimens fro m 27 dogs investigated for leptospirosis were studied: 3 samples gave nonspecific hemagglutination, but for all remaining samples, the resul ts of IHA and an IgM ELISA were concordant. Performance of IHA was sim ple, and IHA requires no specialized equipment, It represents a useful assay for laboratories which require a leptospiral diagnostic capabil ity but lack the expertise to perform specialist investigations.