Impact of urban heat island effect on dengue incidence: a remote sensing approach using thermal and high-resolution optical imagery

Dengue fever, identified by the World Health Organization as a significant global health threat, is the fastest-spreading mosquito-borne viral disease transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Annually, 100-400 million cases are reported, with over 14 million cases and 10,000 deaths in 2024 alone, highlighting the public health challenge of dengue, especially in tropical and subtropical urban areas. The Urban Heat Island (UHI) effect is a critical factor in dengue transmission, creating favorable conditions for Aedes mosquitoes. This study examines the impact of UHIs on dengue incidence at Thanjavur Municipal Corporation, Tamil Nadu, India, via remote sensing-derived Land Surface Temperature (LST) and epidemiological data from 2017 to 2023. High-resolution thermal and optical imagery was used to assess spatial variations in urban surface temperature, whereas dengue incidence patterns were analysed through hotspot detection and statistical analysis. The study also examines land use and land cover characteristics in modulating dengue risk. The findings revealed strong positive correlations between UHIs, built-up zones, and dengue hotspots. UHI analysis revealed that dengue incidence is highest in areas with moderate heat exposure, not in urban cores with extreme temperatures; only 30.2% of dengue cases occurred within UHI zones, suggesting that extreme temperatures (> 48 °C) may suppress Aedes mosquito survival. The land use analysis revealed that built-up areas (45.85%) were strongly correlated with dengue cases (𝜌 = 0.822, p < 0.01), whereas vegetation (40.98%) and water bodies (2.82%) were negatively correlated, indicating their role in influencing dengue transmission. The findings underscore the critical influence of UHIs on dengue incidence and the need for targeted interventions, including dengue-sensitive urban planning focused on maintaining green spaces, ensuring proper drainage, and minimising water stagnation to balance vegetation benefits with vector control.