Spatiotemporal macroecological patterns of Aedes aegypti and dengue fever in a subtropical region of Brazil: seasonal synchrony of larval-positive sites and limited predictive capacity of entomological surveillance.

Dengue fever is an increasingly significant public health challenge in subtropical regions. This study investigates the spatiotemporal macroecological patterns of Aedes aegypti infestation and dengue cases in Santa Catarina, Brazil, from 2015 to 2024, to assess the seasonal synchrony of vector infestation and the predictive capacity of entomological surveillance. Using circular statistics, correlation analysis, non metric multidimensional scaling (NMDS) ordination, and Autoregressive Integrated Moving Average with exogenous variables (ARIMAX) modeling on data from 17 Health Regions, we identified a highly synchronized seasonal peak in Ae. aegypti positive breeding sites (PBS), predominantly in March. However, dengue incidence showed no consistent seasonal pattern. Spatial synchrony in Ae. aegypti positive breeding sites occurrence was observed statewide, with the greatest temporal similarity among western regions. On the other hand, the temporal correlation between Ae. aegypti positive breeding sites and dengue cases was weak and heterogeneous; predictive models were significant in only six of 17 regions and largely underestimated the major 2024 outbreak. We conclude that while Ae. aegypti infestation is predictably seasonal, the vector larval abundance alone has limited utility for forecasting dengue outbreaks. These results highlight the need for surveillance systems to integrate virological, serological, and climatic data alongside entomological indicators for effective early warning.