Evaluation of a Genus Specific rGroEL 1-524 IgM-ELISA and Commercially ELISA Kits During Course of Leptospirosis in Thailand

This work, we developed a genus-specific rGroEL 1-524 IgM-ELISA assay for using as screening diagnosis of suspected leptospirosis among acute undifferentiated febrile illness patients during acute fever. Ddiagnostic accuracies of rGroEL 1–524 IgM-ELISA, and commercial Panbio IgM-ELISA, and Virion-Serion Classic IgG-ELISA were evaluated with Thai 107 leptospirosis sera, and 189 controls, compared to reference culture and/or MAT methods. Sensitivities were 91.7%, 59.6%, and 17.7% for acute- infection, and were 97.1%, 54.8%, and 9.7% for early detection at 1-3 days post-onset of symptoms (DPO1-3), and the specificities were 87.5%, 86.6%, and 74.8% among controls, respectively. The rGroEL 1-524 IgM-ELISA had high sensitivity, at 95.9% and 91.2% among culture and MAT negative cases. Impaired specificity on scrub typhus, possibly from antibody-cross reaction to ortholog GroEL. Commercial Panbio IgM-ELISA had sensitivities of 50%, 63.2%, and 89.9% compared with culture, MAT-negative and single MAT-positive cases whereas Virion-Serion IgG-ELISA provided sensitivities of 13.3%, 10.5% and 71.4%, respectively. A rGroEL 1-524 IgM-ELISA could be useful as a screening test for early diagnosis. The performance of the commercial ELISA suggests the applicability of IgM-ELISA for diagnosis, while IgG-ELISA is useful for seroprevalence surveys. However, confirmation by reference tests is recommended.