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Comparison of NS1 Antigen Detection by RDT and ELISA and its Concordance with RT-PCR for the Early Diagnosis of Dengue in Ananthapuramu District, Andhra Pradesh, India

Introduction: Early detection of dengue fever is important for effective clinical care and vector control. For the detection of dengue viral antigen and antibodies, several serological techniques based on the concept of immunochromatography and Enzyme-Linked Immunosorbent Assays (ELISA) are routinely utilised. The performance of these tests depends on the sensitivity and specificity. Aim: To compare Non Structural protein-1 (NS1) antigen detection by Rapid Diagnostic Tests (RDTs) and ELISA and its association with Real-Time Polymerase Chain Reaction (RT-PCR). Materials and Methods: This diagnostic cross-sectional study was done on 100 clinically suspected cases of Dengue between July-November 2021 at a tertiary care hospital in Ananthapuramu, Andhra Pradesh, India. All the sera samples were collected and subjected to NS1 antigen detection test by rapid test, NS1 ELISA, and RT-PCR, and also serotypes DENV-1, 2, 3, 4 were detected from serum sample by RT-PCR test. The results of rapid and ELISA tests were compared with RT-PCR. Data was analysed by Statistical Package for the Social Sciences (SPSS) version 16.0. Results: Out of total 100 samples, 29 samples were tested positive by NS1 rapid test, 30 samples were tested positive by NS1 ELISA, and 32 samples were tested positive by RT-PCR. The sensitivity, specificity of dengue NS1 antigen rapid test were 87.50% and 98.52%, respectively when compared to RT-PCR whereas that of NS1 ELISA were 93.75% and 100% when compared to RT-PCR. Out of 32 samples tested positive by RT-PCR, two samples were positive for DENV-1, 26 samples were positive for DENV-2, and four samples were positive were DENV-3. Conclusion: The NS1 ELISA test requires extra procedures and time. RDTs need a one-step operation that takes roughly 15-30 minutes. Despite the fact that RT-PCR and ELISA have better performance than RDTs, RDTs are more effective for early diagnosis and therapy of dengue fever in countries with limited infrastructure and in remote places.