Climate Change and Vector-Borne Disease: A Five-Year Surveillance and Cohort Analysis Across Five Districts: Dengue and Malaria Patterns, Climate-Disease Relationships, and Determinants of Outbreak Risk

Climate change is reshaping the geography and intensity of vector-borne diseases globally, with dengue and malaria the two infections most directly responsive to temperature, rainfall, and humidity. South Asian populations face particular burden given the combination of climate vulnerability, dense urban settlement patterns, and operational challenges in vector control. We undertook a 5-year combined surveillance and cohort analysis across five districts representing a geographic gradient from urban metropolitan to forested tribal. Across 60 months of surveillance, dengue incidence rose substantially year-on-year with peak monthly rates rising from 168 to 358 cases per 100,000 across the audit period. Malaria incidence showed similar but less marked rise. Seasonal patterns were strongly evident with post-monsoon peaks driving the majority of annual case load. Monthly temperature was strongly correlated with combined case incidence (r = 0.74). Geographic gradients showed rising prevalence from urban to forested districts. Strongest predictors of district-month outbreak included high rainfall, high temperature, high humidity, standing water sites, forest fringe setting, inadequate solid waste management, and prior-year incidence. Larval source management and community awareness were strongly protective. The findings support climate-adapted vector-borne disease control programmes including geographically-targeted vector surveillance, community engagement, and structural environmental interventions.

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