Sensitivity and specificity of three ELISA-based assays for discriminating primary from secondary acute dengue virus infection

BackgroundDiscrimination between primary and secondary dengue virus infection traditionally has been performed using the hemagglutination inhibition (HI) test. However, this test has practical limitations and disadvantages.ObjectiveTo evaluate the ability of three ELISA-based methods (IgG avidity test, IgM/IgG ratio and IgG titer) to discriminate primary from secondary dengue infection.Study designSerum samples from convalescent-phase patients with confirmed acute, primary (n = 46) or secondary (n = 33) dengue virus infection were tested using three ELISA-based methods. A ROC curve was employed to establish the cut-off points and to evaluate the ability of the three methods to distinguish between acute, primary and secondary dengue virus infection.ResultsAll three assays exhibited sensitivity and negative predictive values of 100% for defining secondary infection. The specificity and positive predictive values were respectively 97.8% and 93.7% for the IgG avidity test, 95.7% and 88.2% for the IgM/IgG ratio assays, and 97.8% and 93.7% for the IgG titer assay.ConclusionAll three ELISA-based assays proved reliable tools for discriminating between acute, primary and secondary dengue virus infection when using serum samples from convalescent-phase patients.