Climate and environmental drivers of dengue expansion in São Paulo, Brazil: An ecological niche modelling approach

Dengue outbreaks in São Paulo State are expanding, driven by a complex interplay of environmental and demographic factors. This study employs an ecological niche model (ENM) to investigate the drivers of dengue suitability across three major epidemic years: 2011, 2015, and 2019. Utilising a robust methodological framework, including semi-annual environmental data and spatially explicit cross-validation, it was found that population density was the most influential predictor of outbreak suitability in all three years (63.4% contribution in 2011, 91.6% in 2015, and 48.6% in 2019). Secondary drivers shifted between epidemics, with maximum temperature being most relevant in 2011 (26.3%) and the Normalised Difference Vegetation Index (NDVI) gaining importance in 2019 (18.5%). Spatially, the analysis revealed a highly dynamic risk landscape, characterised by a massive statewide expansion of high-suitability zones in 2015, followed by a significant contraction and northward shift in 2019. The model's predictive performance was strong for 2011 and 2015, but declined in 2019, suggesting a less distinct environmental signature for that year's outbreak. These findings indicate that urban structure is the primary determinant of dengue suitability, while climatic and vegetation factors modulate risk differently across epidemics with varying characteristics.