Territorial Persistence of Residual Plasmodium falciparum Transmission in the Americas: A One Health Perspective.

Malaria reduction in the Americas has slowed despite sustained elimination efforts, suggesting important changes in the spatial organization of residual transmission. This study evaluated whether declining Plasmodium falciparum incidence between 2000 and 2023 was associated with increasing geographic concentration, spatial clustering, and territorial persistence across the region, with detailed subnational analysis in Colombia. Temporal trends were assessed using segmented regression, geographic concentration using Gini and Herfindahl-Hirschman indices, and spatial dependence using Moran's I and local indicators of spatial association. A Municipal Persistence Index (MPI) was developed to identify municipalities characterized by recurrent high transmission over time. Regional incidence declined by 62.7% but showed progressive temporal deceleration, while more than 80% of cumulative burden remained concentrated in four countries. Since 2020, Colombia has contributed nearly 40% of all reported P. falciparum cases in the Americas. Within Colombia, high-persistence municipalities largely overlapped with statistically significant spatial clusters concentrated along the Pacific region. These findings suggest that residual P. falciparum transmission is increasingly organized into territorially structured persistence systems rather than diffuse endemicity. Advancing malaria elimination may therefore require territorially coordinated One Health strategies aligned with the spatial organization of residual transmission.