Indigenous Territories can safeguard human health depending on the landscape structure and legal status

Indigenous Territories are crucial for preserving biodiversity, particularly in tropical regions, yet their contribution to human health is poorly understood. Using 20 years of data on fire-related and zoonotic/vector-borne diseases, we evaluated how Indigenous Territories, their legal recognition status, and landscape parameters affected disease incidence in the Amazon biome. Overall, we found that Indigenous Territories extent had complex and non-linear effects, with a potential to reduce fire-related disease incidence and to increase zoonotic/vector-borne diseases, depending on the local landscape structure. For instance, Indigenous Territories within municipalities with high forest cover outside their boundaries can mitigate the impacts of particulate matter with less than 2.5 micrometer on human health and reduce the incidence of fire-related diseases. For zoonotic/vector-borne diseases, both forests inside and outside Indigenous Territories, when covering over 40% of a municipality, can contribute to reducing the negative effects from edge density on disease incidence. Our findings emphasize the complex relationships between conservation and human health, which vary based on the local context and Indigenous Territories legal recognition, and underscores the importance of Indigenous Territories and their legal acknowledgment for supporting ecosystem and human health, particularly in landscapes with high forest integrity and low fragmentation. Indigenous territory extent in the Amazon biome can reduce the incidence of fire-related and zoonotic/vector-borne diseases, but only in certain contexts, according to an analysis of disease incidence data from the region.