Estimation of the sensitivity and specificity of a Leptospira spp. in-house ELISA through Bayesian modelling

The microscopic agglutination test (MAT) is still considered the gold standard for the diagnosis of leptospirosis, although studies have shown that the test is an imperfect gold standard for clinical samples and unsuitable for epidemiological studies. Here, test characteristics of an in-house ELISA were identified for both subclinical and clinical populations by Bayesian latent class models. A conditional dependence model for two diagnostic tests and two populations was adapted to analyse a clinical and a subclinical scenario, respectively. These Bayesian models were used to estimate the sensitivity and specificity of the in-house ELISA and the MAT as well as the prevalences. The Bayesian estimates of the in-house ELISA were: clinical sensitivity = 83.0%, clinical specificity = 98.5%, subclinical sensitivity = 85.7% and subclinical specificity = 99.1%. In contrast, the estimates of the MAT were: clinical sensitivity = 65.6%, clinical specificity = 97.7%, subclinical sensitivity 54.9% and subclinical specificity = 97.3%. The results show the suitability of the in-house ELISA for both clinical investigations and epidemiological studies in mildly endemic areas.