Background: Discrimination 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.
Objective: To 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 design: Serum 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.
Results: All 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.
Conclusion: All 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.