Spatiotemporal Evolution and Emergence of Frontier Malaria Mosaics in the Brazilian Amazon

Malaria is a major global health problem, including the Brazilian Amazon region. The theory of frontier malaria-linking agricultural expansion, migration, and road networks to altered land cover and disease transmission-is increasingly inadequate for contemporary Amazonian frontiers. Instead, we propose the concept of frontier malaria mosaics, reflecting diverse occupational profiles, mobility patterns, rural-urban connectivity, and land uses. As malaria declines in the Amazon, transmission becomes highly focal, clustering in localized areas with distinct characteristics. Using locality-level data from Brazil's Malaria Surveillance System and a novel method to identify nearly all case locations, we analyze spatiotemporal evolution via parasite species, infection origin, land use, settlement patterns, and sociodemographics. Annualized indicators enable cross-period comparisons. Through cluster regionalization, we reveal distinct low- and high-transmission mosaics, each shaped by successive government policies. This approach overcomes key data limitations and demonstrates how local spatial configurations scale into regional patterns over time.