Assessment of Molecular Prevalence of Dengue Serotypes Among the Viremia Cases of YSR Kadapa District of Andhra Pradesh, India by TaqMan Assay

Background: Dengue is a major public health concern in India, with dynamic shifts in circulating serotypes influencing outbreak patterns and disease severity. Molecular surveillance plays a crucial role in identifying dominant serotypes during viremic phases of infection. The objective is to determine the molecular prevalence and distribution of dengue virus serotypes among NS1-positive viremic cases in YSR Kadapa district and to assess concordance between NS1 ELISA and RT-PCR. Material and Methods: A cross-sectional study was conducted at a tertiary care teaching center. Serum samples from NS1 antigen-positive patients were analyzed by serotype-specific real-time RT-PCR with TaqMan probes. Demographic distribution and serotype prevalence were analyzed. Chi-square test was used to assess associations between age groups and serotype distribution. Results: Among RT-PCR–confirmed cases, DENV-3 was the predominant serotype (75%), followed by DENV-2 and DENV-4. Co-circulation of multiple serotypes was observed, indicating a hyperendemic transmission pattern. The highest proportion of cases occurred in the 0–10-year age group. No statistically significant association was found between age group and serotype distribution (p > 0.05). A discordance rate of 36% was observed between NS1 ELISA and RT-PCR results. Conclusion: The predominance of DENV-3 and co-circulation of other serotypes highlight ongoing serotype dynamics in YSR Kadapa district. Periodic molecular surveillance at designated laboratories may enhance outbreak detection and epidemiological monitoring in endemic regions.

Keywords: Dengue virus; Serotype distribution; Real-time RT-PCR; NS1 antigen; Molecular surveillance.