IgM Dot-ELISA Assay using prevalent Leptospira strain for diagnosis of leptospirosis

Background: A test strip IgM Dot-ELISA assay for the detection of leptospire-specific IgM antibodies in human sera was developed. Antigen dotted on a nitrocellulose paper strip was the sonicated antigen prepared from Leptospira serovar prevalent in this area, i.e., Icterohaemmorhagiae.Objective: The aim of this study was to evaluate an in- house prepared IgM Dot- ELISA test strip for the diagnosis of leptospirosis.Material and methods: The ability of the IgM Dot- ELISA to diagnose leptospiral infection was evaluated by testing 125 serum samples, 75 serum samples from 93 laboratory-confirmed leptospirosis case patients with positive result in the standard microscopic agglutination test (MAT) and 25 serum samples from patients with various diseases other than leptospirosis and 25 from healthy individuals. The results of Dot- ELISA were also compared to that of a commercially available IgM ELISA.Results: Using the results of the MAT as a gold standard, the sensitivity and specificity of the test strip IgM dot-ELISA assay were 97.33% and 96.00%, respectively. The assay showed relatively good negative predictive values (96.00%) thus making the assay ideally suited for rapid screening.Conclusion: In conclusion, the test strip IgM dot-ELISA assay was sensitive enough for use as a screening test for serodiagnosis of leptospirosis. The assay was simple, inexpensive, and easy to perform for both a single test format and a large number of specimens.