Evaluation of indirect immunofluorescence assay for diagnosis of human leptospirosis.

Abstract

Introduction. The diagnosis of leptospirosis is difficult because it presents an extremely broad spectrum of symptoms. A number of diagnostic serological assays have been developed, but their performance and utility have not been evaluated in Colombia.
Objectives. To evaluate the IgM-IgG-indirect inmunofluorescence assay to detect antibodies against Leptospira in human serum samples and to diagnose leptospirosis.
Materials And Methods. A panel of 19 sera from leptospirosis cases with clinical diagnosis and positive microscopic agglutination test, 40 samples from individuals without history of leptospirosis and negative microscopic agglutination test, and 96 samples from patients with other infectious diseases were evaluated.
Results. The sensitivity of the indirect inmunofluorescence assay was 89.47%, its specificity was 100%, the negative predictive value was 95.2% (CI 95% 82.6-99.2), and its positive predictive value was 100%. At the same time an exploratory study of 27 samples from different febrile syndromes, 11% were positive by IgM-indirect inmunofluorescence assay against Leptospira.
Conclusions. The data indicate that indirect inmunofluorescence assay is useful as a diagnostic adjunct to clinical diagnosis and for seroepidemiologic studies. The presence of IgM antibodies against Leptospira in sera from cases of febrile syndrome indicate that leptospirosis is one of the causes of this syndrome and should be considered by the clinician.