Disentangling climate's dual role in dengue dynamics: A multiregion causal analysis study.

Dengue fever poses major public health challenges, with climate change complicating control efforts. Yet, the full extent of climate change's impact on dengue remains elusive. To investigate this, we used an advanced causal inference method to 16 diverse climatic regions in the Philippines. This method is capable of detecting nonlinear and joint effects of temperature and rainfall to dengue incidence. We found that temperature consistently increased dengue incidence throughout all the regions, while rainfall effects differed depending on the variation in dry season length, a factor previously overlooked. Specifically, our results showed that regions with low variation in dry season length experience a negative impact of rainfall on dengue incidence likely due to strong flushing effect on mosquito habitats, while regions with high variation in dry season length experience a positive impact, likely due to increased mosquito breeding sites. Our findings emphasize the need for tailored prevention strategies based on local climate conditions, rather than a one-size-fits-all approach.