Diagnosis of Dengue by Serology (NS-1 Antigen and IgM ELISA) and Identification of Serotypes by RT-PCR at a Tertiary Care Hospital, Jaipur, Rajasthan

Abstract

Introduction: In India there are four distinct dengue viruses (DENVs) serotypes prevalent that can cause a full spectrum of disease from a subclinical infection to a mild self-limiting disease. The present study aimed to detect the dengue NS1 antigen by ELISA to screen the presence of dengue-specific IgM antibodies by IgM antibody capture ELISA (MAC-ELISA), and to detect dengue viral RNA in sero-positive samples and identify serotypes by one step multiplex real time reverse transcriptase-polymerase chain reaction (RT-PCR). Methodology: A hospital based observational, descriptive study was carried out on a total of 260 blood samples of clinically suspected patients with complaints of fever, myalgia, rash, and/or arthralgia. Detection of dengue NS 1 antigen and IgM antibody were done and then dengue viral RNA detection and serotype identification in seropositive samples was done to look for prevalent strain in the study area. All these methodologies were followed as per manufacturer's kit. Results: Out of 260 blood samples, a total of 82 (31.5%) samples tested positive for both sero-markers of dengue infection. Among these 82, 53 (64.6%) samples tested positive for NS1 antigen, 8 (9.8%) for IgM antibody alone, and 21 (25.6%) for both NS1 antigen and IgM antibody. PCR testing was done for these 82 seropositive patients and out of these, 75 (91.5%) tested positive on PCR testing. Of these 75 samples, 84% tested positive for dengue serotype-2 and only 16% tested positive for dengue serotype-1. Conclusion: In the study area, DENV-2 is more prevalent followed by DENV-1. None of the samples tested positive for serotype-3 and serotype-4. There was no coinfection in any sample. The information of predominant serotypes can guide in forecasting dengue outbreaks and improving control measures of vectors and thus may be helpful in the prevention of outbreaks.

Keywords

• Dengue, DENV, IgM antibody, NS-1antigen, RT-PCR, Serotype.