The 2011 outbreak of dengue virus infection in Malwa region of Punjab, India-an evaluation of various diagnostic tests

ObjectiveTo compare the efficacy of rapid immunochromatographic test (ICT) and ELISA for detection of dengue specific parameters (NS1 antigen and IgM antibodies) and the association of these parameters with thrombocytopenia.MethodsA total of 1787 serum samples were obtained from the same number of clinically suspected cases of dengue during an outbreak (2011) of dengue in the Malwa region of Punjab. All the samples were subjected to rapid ICT, dengue early ELISA and dengue IgM-capture ELISA for detection of NS1 antigen and IgM antibodies. Platelet counts of all the cases positive for dengue infection and 150 cases negative for dengue parameters (control group) were recorded.ResutlsRapid ICT for NS1 antigen detection showed same specificity (100%) but lower sensitivity (85.81%) than the dengue early ELISA, while it was 100% and 94.10% respectively for IgM antibody detection. The difference in the platelet counts of cases positive and negative for dengue specific parameters was stastically insignificant (standard error of proportions=0.017, Z value=0.84, P value=0.2).ConclusionsThe confirmation of serological diagnosis of dengue should always be based on ELISA test and ICT and/or thrombocytopenia should not be used as a stand-alone test.