The Human Footprint and Climate Change Shape Current and Future Scenarios of Visceral Leishmaniasis Distribution in Doce River Basin in Brazil.

The identification of factors that influence the distribution of visceral leishmaniasis (VL) is key for future surveillance and control. This study sought to understand how environmental and climate variables can interfere with VL expansion in the Doce River basin located in Brazil. This ecological study explored the influence of anthropogenic, environmental, and climatic factors on VL expansion. Ecological niche modeling was used to assess the current situation and predict the future spread of the disease. The study used 855 human cases of VL recorded in the Doce River basin from 2001-2018 and analyzed them within the context of climatic and environmental variables. To model the current and future distributions, MaxEnt with the kuenm R package was used. To model the future projections, the global climate model of the National Centre for Meteorological Research (CNRM-CM6-1) was used as well as two Shared Socioeconomic Pathways (SSP370 and SSP585) for 2021-2040 and 2061-2080. Variables that contributed to the VL distribution were the human footprint index (62.6%), isothermality (28.1%), precipitation during the wettest month (6.4%), and temperature during the hottest month (3.8%). Future climate change scenarios showed areas suitable for the disease increasing over time (by about 7% between 2021 and 2041 and about 12% between 2061 and 2080) and the maintenance of the disease in places already considered endemic. Our results demonstrate the importance of anthropic and climatic factors in VL expansion. We hope that these results will contribute to boosting surveillance and vector control programs along the Doce River basin.