Human mobility, garimpos and spatiotemporal malaria transmission in the Yanomami Indigenous Territory: a retrospective observational study.

Abstract

Past research on human mobility and malaria transmission often used coarse spatial scales, limiting effectiveness for targeted control strategies - especially as transmission becomes more localized with lower incidence. This is seen in Brazil's Yanomami Indigenous Territory (YIT), where illegal gold mining (<i>garimpo</i>) and weakened environmental policies have contributed to malaria resurgence. We used epidemiological surveillance data to identify and distinguish localities of likely infection and residence within and near the YIT. We then constructed Malaria Mobility Networks (MMNs) to analyse spatiotemporal malaria transmission patterns from 2007 to 2023. MMN quantified diffusion effects and differentiated between autochthonous and imported malaria cases among localities. Integrating malaria and population location data into a regular grid improved the accuracy of malaria risk and transmission assessments. We observed spatial concentration of malaria cases (86%) and population (91%), and most grids have incorrectly attributed malaria (94%) and population (86%) risks. We improved spatial identification of malaria cases in 12% (70% in <i>garimpos</i>) and corrected 20% inaccurate coordinates. Autochthonous malaria in indigenous localities reached 90% (2023), the highest MMN share compared to total cases. MMN involving infection in <i>garimpos</i> raised since 2019 and peaked around 27% in 2022, being more associated with urban residence. Spatial analysis reveals spatiotemporal linkages between residence-based human mobility and malaria, supporting improved epidemiological surveillance. MMN demonstrates how spatiotemporal patterns of malaria transmission aligns with <i>garimpo</i> dynamics and their regional connections. Persistent malaria in indigenous localities stems from interactions with <i>garimpos</i> within the YIT and robust <i>garimpo</i>-urban networks that facilitate disease transmission. <i>Bolsa de Produtividade de Pesquisa</i> (grant number PQ 306567/2016-4), Brazilian National Research Council (CNPq).