Large hydropower dams’ construction, population mobility and exported malaria cases across space and over time in the Brazilian Amazon

Brazil carried out, during the first two decades of the 21st century, massive public investments on infrastructure projects such as large hydropower dams, with repercussions on population health. Here we characterize and quantify the mobility patterns associated with malaria occurrence and spread to distant areas due to large hydropower dams’ construction in two study sites in the Brazilian Amazon: Porto Velho municipality (PVH), in Rondônia state, where Santo Antônio and Jirau dams were built (2008-2013); and Altamira region (ATM), in Pará state, where Belo Monte dam construction (2011-2016) took place. The period of analysis covers 4 years before, 6 years during and 4 years after each dam’s construction. We analyze malaria cases by type: imported, autochthonous (locally infected) and exported cases. To fill a gap in the literature, we focus on exported cases. We utilize malaria case notifications entered into the electronic malaria notification system of the Ministry of Health of Brazil between January 2004 and December 2020. We apply Pearson’s Chi-Square test of differences and logistic regression to assess sociodemographic and epidemiologic characteristics of the exported malaria cases. Our results show that during dams’ construction malaria cases steadily fell. Yet, in ATM, a recent increase of autochthonous cases was observed. Besides, PVH presented higher potential for malaria to spread through exported cases especially during the construction period. Exported malaria cases were mostly males; 16+ years old; usually asymptomatic; literate; and whose economic activities are related to mining, agriculture or traveling. This profile can inform public policies in this and similar settings to target these mobile population groups with active surveillance strategies, providing early diagnosis and immediate treatment, and avoiding the spread of malaria.