Evaluation of an indirect hemagglutination test for the diagnosis of human leptospirosis.

A presumptive hemagglutination test for the serological diagnosis of leptospirosis in humans is described. The antigen was prepared from a soluble alcohol extract of an andamana strain sorbed to human O-negative erythrocytes and preserved by pyruvic aldehyde fixation. In this study, the overall sensitivity of the hemagglutination test was 92% in contrast to 69% for the presumptive slide agglutination test. The specificity was 95% for the hemagglutination test in comparison with 83% for the slide test.