Comparision of Diagnostic Efficacy of Ns1 Antigen Based Immunochromatographic Test With Immuno-Sorbent Assay and Its Role in Detection of Early Dengue Infection

Abstract

ABSTRACT:INTRODUCTION:Dengue is an acute viral infection with potential fatal complications. Rapid and easy diagnosis of dengue can help in patient triage and caremanagement. The detection of dengue virus NS1 antigen by rapid lateral flow tests offers a faster method to a presumptive diagnosis in the peripheral centers of developing countries like India where the laboratory has no great technological backup. MATERIALS AND METHODS: A total of 351 sera from patients suspected of having dengue virus infection were tested for dengue NS1 antigen and dengue IgM and IgG antibodies by both ELISA and immunochromatographic test (ICT). RESULTS: From the 351 samples tested, 249 (70.94%) of the sera were found to be positive for DENV infection based on the IgM antibody or IgG antibody or NS1 antigen. Of the 249 samples 105 (42.16%) were positive for only IgM or only IgG or both antibodies by ELISA and 101 (40.56%) by ICT. Based on dengue NS1 antigen along with IgM and/or IgG tests, 144 (57.8%) were positive for dengue infections by ELISA and 139 (55.8%) by ICT. Among these 144 samples, only dengue NS1 antigen was detected in 67 (26.90%) by ELISA and 65 (26.10%) by ICT. CONCLUSIONS: Inclusion of NS1 in the diagnosis of dengue increases the detection rate significantly. The sensitivity of ICT for both antigen and antibody detection are almost equal to ELISA. Thus, the potential use of the NS1 antigen along with antibody tests in an ICT could increase the diagnostic efficiency for early diagnosis of dengue infection.

Comparison of NS-1 Antigen Detection by ICT and ELISA for Evaluating Acute Dengue

“…With its high specificity (99.5%) and positive predictive value (PPV) (99.6%), they recommend the use of rapid immunochromatography test device for diagnosing a population group defined by clinical symptomatology of acute dengue infection. In concordance, our study also saw a higher specificity of 91.66% for NS1 ICT in comparison to 87.5% for NS1 ELISA as were studies by other authors (Kulkarni et al, 2011;Chakraverti et al, 2012). PPVs for both NS1 tests were below 80% but by ICT the values were higher at 79.31% whereas ELISA results was marginally lower at 73.52% in agreement with Zainah et al, (2009).…”

“…In defiance of the results of the present study, no statistically significant superiority was noted in NS1 antigen detection by either the immunochromatography card or the immunosorbent assay over each other in agreement with Hang et al, (2009). Despite investigators Kulkarni et al, (2011) andChakraverti et al, (2012) having noted that there is no necessity to repeat the test once results have been declared positive by NS1 since it is a highly specific marker of dengue infection, other authors such as Osorio et al, (2010) point out variability in their sensitivity (ranging between 37% and 98.9%) attributable in part by the fact that sensitivity decreases with time after fever onset and in secondary infections. Addition of an IgM test alongside NS1 test improves the sensitivity by being complimentary to NS1 in such situations.…”

Dilemma in laboratory diagnosis of Dengue, Chikungunya and Zika viruses

“…Kumar et al and Chakraverti et al found no significant difference in sensitivity and specificity between ICT and ELISA tests for detection of dengue infection. 46,47 Serum is the most common sample type. In DENV infections the Dengue Virus NS1 ELISA is an important early screening test, which is possible from day 1 to approximately day 18 after onset of symptoms that helps to minimize the diagnostic gap between RT-PCR and antibody positivity.…”