Diagnosis of human leptospirosis: systematic review and meta-analysis of the diagnostic accuracy of the Leptospira microscopic agglutination test, PCR targeting Lfb1, and IgM ELISA to Leptospira fainei serovar Hurstbridge

Abstract

Background: Leptospirosis is an underdiagnosed infectious disease with non-specific clinical presentation that requires laboratory confirmation for diagnosis. The serologic reference standard remains the microscopic agglutination test (MAT) on paired serum samples. However, reported estimates of MAT's sensitivity vary. We evaluated the accuracy of four index tests, MAT on paired samples as well as alternative standards for leptospirosis diagnosis: MAT on single acute-phase samples, polymerase chain reaction (PCR) with the target gene Lfb1, and ELISA IgM with Leptospira fainei serovar Hurstbridge as an antigen.

Methods: We performed a systematic review of studies reporting results of leptospirosis diagnostic tests. We searched eight electronic databases and selected studies that tested human blood samples and compared index tests with blood culture and/or PCR and/or MAT (comparator tests). For MAT selection criteria we defined a threshold for single acute-phase samples according to a national classification of leptospirosis endemicity. We used a Bayesian random-effect meta-analysis to estimate the sensitivity and specificity of MAT in single acute-phase and paired samples separately, and assessed risk of bias using the Quality Assessment of Studies of Diagnostic Accuracy Approach- 2 (QUADAS-2) tool.

Results: For the MAT accuracy evaluation, 15 studies were included, 11 with single acute-phase serum, and 12 with paired sera. Two included studies used PCR targeting the Lfb1 gene, and one included study used IgM ELISA with Leptospira fainei serovar Hurstbridge as antigen. For MAT in single acute-phase samples, the pooled sensitivity and specificity were 14% (95% credible interval [CrI] 3-38%) and 86% (95% CrI 59-96%), respectively, and the predicted sensitivity and specificity were 14% (95% CrI 0-90%) and 86% (95% CrI 9-100%). Among paired MAT samples, the pooled sensitivity and specificity were 68% (95% CrI 32-92%) and 75% (95% CrI 45-93%) respectively, and the predicted sensitivity and specificity were 69% (95% CrI 2-100%) and 75% (2-100%).

Conclusions: Based on our analysis, the accuracy of MAT in paired samples was not high, but it remains the reference standard until a more accurate diagnostic test is developed. Future studies that include larger numbers of participants with paired samples will improve the certainty of accuracy estimates.

Keywords: Agglutinations tests; Enzyme-linked immunosorbent assay; Leptospirosis; Meta-analysis; Polymerase chain reaction; Sensitivity and specificity; Systematic review.

Fig. 1

Study flow diagram for systematic review of studies evaluating the diagnostic accuracy of MAT, PCR, and IgM ELISA, published global and between 1950–2022. A Flow diagram of the selection process of MAT studies. B Flow diagram of the selection process of PCR studies. C Flow diagram of the selection process of IgM ELISA studies

Fig. 2

Forest plot of estimated and pooled sensitivity and specificity of studies evaluating the diagnostic accuracy of MAT in single acute-phase samples, published global and between 1950–2022

Fig. 3

Roc curve of pooled and predicted sensitivity and specificity of studies evaluating the diagnostic accuracy of MAT in single acute-phase samples, published global and between 1950–2022

Fig. 4

Forest plot of estimated and pooled sensitivity and specificity of studies evaluating the diagnostic accuracy of MAT in paired samples, published global and between 1950–2022

Fig. 5

Roc curve of pooled and predicted sensitivity and specificity of studies evaluating the diagnostic accuracy of MAT in paired samples, published global and between 1950–2022