Dot-ELISA for human leptospirosis employing immunodominant antigen.

A dot enzyme-linked immunosorbent assay which uses a proteinase-K resistant antigen (PK-Dot-ELISA) to detect antileptospiral IgM antibodies was compared to the microscopic agglutination test (MAT). The assay was evaluated in serum samples from patients with leptospirosis (n = 89), typhoid fever (n = 10), malaria (n = 19), syphilis (n = 20), hepatitis (n = 16) and clinically healthy individuals (n = 92). The PK-Dot-ELISA presented a sensitivity of 92.1% and a specificity of 97.5%. The overall results of the PK-Dot-ELISA were similar to those of the MAT. However, the PK-Dot-ELISA was capable of detecting antibody activity in 43% of acute-phase sera which were negative by the MAT. Our data suggest that PK-Dot-ELISA can be used as an important portable field serodiagnostic assay for acute leptospirosis.