Pan- India molecular surveillance of dengue serotypes, 2023-2025.

BACKGROUND

The four serotypes of dengue virus are a significant public health challenge in India, with regional variability in serotype circulation and limited comprehensive spacio-temporally harmonized data across diverse geographic areas. Thus, a nation-wide pan-India passive molecular surveillance study was conducted in 45 of 165 Virus Research and Diagnostic Laboratories (VRDLs), in 25 states and union territories between 2023 and 2025.

METHODS

A total of 6889 dengue positive serum samples referred to the VRDLs (n = 45) for diagnosis of dengue were tested by Realtime reverse transcriptase PCR for determination of infecting serotypes.

RESULTS

All regions showed co-circulation of multiple serotypes, with eight states having all four serotypes co-circulating. DENV-2 was predominant during the study period. Increased likelihood of thrombocytopenia, arthralgia, and hemorrhagic manifestations were directly associated with concurrent infections with multiple serotypes compared to mono-serotypic infections.

CONCLUSION

These findings underscore the importance of continuous, geographically representative molecular surveillance to monitor evolving dengue serotype dynamics, informing outbreak prediction and guiding dengue vaccine introduction strategies in India.