State level dengue trends and climate epidemiologic associations in India from 2021 to 2024

Background and Objectives: Dengue remains India's most significant arboviral threat, with substantial geographic heterogeneity and climate sensitivity. We conducted a comprehensive state-level analysis of dengue epidemiology (2021-2024), evaluated climate and socioeconomic determinants, and generated evidence-based projections to inform targeted control strategies. Methods: State/UT dengue surveillance data (2021-2024) from the National Vector Borne Disease Control Programme were linked with climate variables (temperature, precipitation) from NASA POWER, socioeconomic indicators (GDP per capita, urbanization), and governance proxies (NITI Aayog SECI). Incidence rates, case fatality rates (CFR), and temporal trends were computed. Multivariable regression modeling evaluated determinants of log-incidence. National projections (2025-2027) were generated using log-linear models with uncertainty quantification. Results: National cases fluctuated from 193,245 (2021) to a peak of 289,235 (2023), declining to 233,519 (2024), with mean CFR of 0.15%. Highest 2024 incidence occurred in Lakshadweep (743/100k), Puducherry (129/100k), and Kerala (58/100k; CFR 0.62%). Temperature (β=0.31, 95% CI: 0.05-0.56, p=0.017) and GDP per capita (β=0.50, 95% CI: 0.28-0.73, p<0.001) were independently associated with log-incidence. Emerging foci included northeastern states (Assam: +2,105%; Manipur: +1,113%) while some traditional endemic states showed decline. Projections estimate 286,000 cases in 2025 (95% CI: 123,000-662,000). Interpretation and Conclusions: Dengue burden in India demonstrates significant spatiotemporal heterogeneity driven by climate and development factors. Climate-informed early warning systems and targeted vector control in emerging foci are essential for optimizing resource allocation.