Epidemiology and immuno-molecular status of Nepal dengue outbreak

Abstract

Background: The emergence and circulation of dengue infection have become one of the major public health concerns in the world with its high prevalence in the sub-tropical and tropical countries. Hundreds of Dengue cases have been reported annually and the shift of serotypes in every year has raised the concern of public health in Nepal. The detection of dengue virus infections and circulation of different serotypes in different areas has a great role for the clinical management of patients, surveillance, and clinical trial assessments in the days to come. Methods and materials: Clinically suspected dengue cases (n = 240) were subjected to sero analysis for anti-dengue IgM, IgG antibody and NS1 antigen followed by IgG end-point ELISA. Viral RNA extraction was performed for all samples using the Qiagen kit. cDNA was prepared, and RT-PCR was performed using D1 and DencomR2 primers. Dengue Serotyping was done for PCR positive samples using gene-specific primers. Results: Out of 240 dengue suspected cases, male (n = 153/63.75%), female (n = 87/36.25%) and children below 10 years (6.25%) were diagnosed as positive by ELISA. NS1 (59.16%), IgM (33%) and IgG (7.9%) were detected by ELISA, however, only 14 samples were positive alone to each test. Most of the cases were found to be of primary infection. Antibody level for each serum was calculated and categorized as high (43228.70), medium and low (953.53). Only 35.83% of the suspected cases were confirmed positive for dengue virus by PCR and were of Dengue Serotype-1 in the year 2016 in Nepal. Conclusion: The single test alone could not be confirmatory as only 35.83% of the clinically suspected cases were confirmed for Dengue virus infection by PCR. This implies that confirmatory tests like PCR should be coupled with the ELISA results for the proper diagnosis and management of the disease.