Changing transmission dynamics among migrant, indigenous and mining populations in a malaria hotspot in Northern Brazil: 2016 to 2020

Abstract

Background Roraima state is the northernmost state in Brazil and the primary border-crossing point between Brazil and Venezuela. The uncontrolled surge of malaria in Venezuela, coupled with mass migration of Venezuelans to neighbouring countries and the upward trend in informal mining in the state, pose a serious threat to the broader region, especially to migrant, indigenous and mining populations, jeopardizing malaria elimination efforts. This study describes changes in the epidemiological profile of malaria in Roraima state related to time, place and populations at risk from 2016 to 2020. Methods De-identified malaria surveillance data were obtained from the Malaria Epidemiological Surveillance System from 2016 to 2020. Pearson’s chi-square tested differences between imported and autochthonous cases. Multivariable logistic regression was used to identify risk factors for imported versus autochthonous cases by demographic characteristics. Results Odds of being an imported case were higher for Plasmodium falciparum cases (AOR = 2.08). However, as the number of cases from Venezuela decreased in 2020 following closure of the border, the proportion of P. falciparum cases increased markedly, from 6.24% in 2019 to 18.50% in 2020. Over the 5-year period, the odds of being an imported case among miners were about nine times higher than the general population (AOR = 8.99). The proportion of total malaria cases that were among indigenous people increased from 33.09% in 2016 to 54.83% in 2020. Indigenous children had a higher burden of malaria with over 40% of cases in children 0 to 9 years old, compared to 8% in non-indigenous children 0 to 9 years old. In some municipalities, place of infection differed from place of notification, with a large proportion of cases in these municipalities reporting in Boa Vista. Conclusions Malaria remains a serious threat in Roraima state, especially among high-risk populations, such as miners, migrants, and indigenous people. As malaria cases have increased among indigenous people and miners, and the proportion of P. falciparum cases has increased, elimination efforts require understanding of these risk factors to tailor interventions appropriately. Furthermore, cross-border surveillance systems need to be urgently strengthened at formal and unofficial border points, especially since the border with Venezuela reopened in July 2021.

Brazilian Amazon indigenous territories under deforestation pressure

“…Combined with setbacks, the rise in the gold price in recent years has increased pressure on these protected areas; in the 2019–2021 period, the gold price increased more than 30%, reaching up to $65 g −1 , the highest value of the last ten years ( https://goldprice.org ). In addition to the environmental impact, the anthropic advance on indigenous territories also serves as a vector of diseases, such as malaria, associated with illegal mining activities, which may decimate indigenous peoples along with their culture and knowledge 45 – 47 .…”

Brazilian Amazon Indigenous Territories under deforestation pressure

“…Combined with setbacks, the rise in the gold price in recent years has increased pressure on these protected areas; in the 2019-2021 period, the gold price increased more than 30%, reaching up to $65 g -1 , the highest value of the last ten years ( https://goldprice.org ). In addition to the environmental impact, the anthropic advance on indigenous territories also serves as a vector of diseases, such as malaria, which is associated with illegal mining activities, may decimate indigenous peoples along with their culture and knowledge [33][34][35] .…”

Temporal Analysis of Malaria Cases in the Brazilian Yanomami Pediatric Population: A Retrospective Ecologic Study From 2003 to 2022

“…8 Nevertheless, the favorable environment for Anopheles species mosquitoes reproduction and dissemination in water reservoirs left in the mines increases the risk of infection among miners. 4…”

“…Moreover, studies have shown that the loss of forest cover is a significant predictor of malaria transmission in the Amazon region, with a higher prevalence of the disease among Yanomami indigenous children and adolescents. 4 In this study, we investigate the incidence of malaria among Yanomami indigenous children and adolescents residing in the Brazilian Legal Amazonia territory.…”