Increase in the number of malaria cases has a direct correlation with illegal mining

After a period of successful malaria control actions in the early 2010s, Roraima began to register, over time, an increase in notifications of the disease. Mainly associated with the advance of illegal mining, the disease began to affect mostly indigenous people, especially the Yanomami. This is what a study conducted by the Oswaldo Cruz Institute (IOC/Fiocruz), Federal University of Roraima (UFRR), and the Graduate Program in Biodiversity and Biotechnology (Bionorte Network), in partnership with the Health Department of Roraima (Sesau/RR) and the Ministry of Health. Published in the scientific journal Malaria Journal, the work analyzed data on malaria in Roraima from 2010 to 2020.

In 2010, the state registered 19,000 cases of malaria with local transmission, with 30% of occurrences (5,700 cases) in indigenous areas. Reflecting the actions taken for the fight against the disease adopted by the National Malaria Control Program, in 2013, notifications dropped to 4,800, with an even lower percentage in territories of indigenous peoples: 1,200 cases, that being, 25% of the records. However, mining has expanded in indigenous land. Based on data from Mapbiomas, the report produced by the Hutukara Yanomami and Wanasseduume Ye'kwana associations points out that the mining area in indigenous land increased more than 30 times between 2016 and 2020. Malaria records have soared. In the first year of the pandemic, while malaria cases were dropping in Brazil and in the Americas, Roraima reached 29,000 cases of the disease, with more than 18,000 notifications – 62% of the total – in indigenous areas.

“These data tell the story of what we have observed and experienced in recent years. Why has malaria grown so much in Roraima? In 2020 alone, mining grew by 30% in the Yanomami Land. The WHO [World Health Organization] announced a drop in cases in the Americas, but we had an increase of more than 40% in local transmission”, says Jacqueline de Aguiar Barros, first author of the article and technician at the Center for Malaria Control in Roraima.

The survey is part of Jacqueline's doctoral research, developed in the Graduate Program in Biodiversity and Biotechnology of the Bionorte Network, with guidance from researchers Fabiana Granja, from UFRR, and Maria de Fátima Ferreira da Cruz, Assistant Head of the Research Laboratory in Malaria of the IOC. Researcher Pedro Pequeno, from the Graduate Program in Natural Resources (Pronat/UFRR), contributed by performing the statistical analysis.

Ideal scenario for transmission of the disease

More than 40% of Roraima's territory consists of indigenous lands, where healthcare is the responsibility of two Special Indigenous Health Districts (DSEI). On the border with Venezuela, there is the DSEI Yanomami, which extends from Roraima to Amazonas. In all, there are 96,000 km² of demarcated land, where approximately 28,000 indigenous people live, most of the Yanomami people. On the border with Guyana is the East DSEI of Roraima, which covers an area of 69,000 km², including the Raposa Serra do Sol Reserve and other territories. There are 52,000 indigenous people living in this region, of seven ethnic groups.

In the DSEI Yanomami area in Roraima, cases of malaria dropped from over 3,000 in 2010 to 404 in 2012. Then, they progressively rose until they returned to a level of over 3,000 in 2018. Illegal mining, which was already growing within the territory, expanded more intensely in the following years, and cases of malaria multiplied. In 2020, there were more than 14,000 records.
Notifications also increased in East DSEI, where, in addition to mining, influenced by Venezuelan immigration. Between 2010 and 2016, cases went from more than 2,000 to just 368. In 2018, there were already more than 3,000 notifications, surpassing 4,000 in 2020.

Study Coordinator Maria de Fátima explains that mining favors the transmission of malaria in several ways. “The miners invade the forest and dig the earth, forming wells that, in turn, function as breeding grounds for the proliferation of anopheline mosquitoes, which transmit malaria. In other words, with more mosquitoes and more people, whose blood serves as food for the mosquitoes, the ideal scenario is created for the transmission of the disease. This happens next to the villages, and the indigenous people start to live close to malaria transmission centers, which did not exist before”, describes the malariologist.

Another problem highlighted by the scientist is the irregular treatment of the disease by miners, which contributes to perpetuating the cycle of malaria in the region. “Miners use drugs of dubious origin to fight the symptoms of malaria that are not assured to be effective and they do not undergo full treatment. Thus, the parasite remains alive in the organism, infecting mosquitoes at the moment of the bite, increasing transmission and selecting parasite populations with potential to create tolerance against antimalarial drugs”, adds the scientist.

Extended alert

In addition to the increase in cases, the researchers observed a rise in the proportion of infections caused by the Plasmodium falciparum. This species of parasite causes the most severe forms of malaria, with the highest risk of death. In 2010, almost 10% of malaria cases in Roraima were caused by the P. falciparum. In the following years, the proportion was reduced. In 2019, the rate was 4.5%. However, in 2020, it jumped to 20%.

“Malaria caused by the P. falciparum is more serious, but the parasite responds well to therapy. With prompt diagnosis and timely treatment, the person is cured and transmission ceases. The increase in cases means difficulty in the access to diagnosis and treatment”, points out Jacqueline.

The researchers point out that the fight against malaria associated with illegal mining goes beyond the health area and requires coordinated actions from different political spheres. “We see that malaria has increased because of mining and, in many places, health teams have been prevented from acting for safety reasons, jeopardizing diagnosis and treatment. It is impossible to solve the problem only with health in this context”, emphasizes Jacqueline.

“It is a problem that involves municipalities, states, as well as the Federal Government”, adds Maria de Fátima. The authors also warn of the possibility of increased resistance to drugs, which could jeopardize malaria control strategies, including Brazil's goal of eliminating the P. falciparum. The next stage of the research will analyze the genome of the parasites in circulation to investigate the presence of genes associated with resistance to the drugs used in malaria therapy. The researchers have already collected samples referring to 206 cases of malaria, of which 197 (95.63%) reported mining activity in the last 15 days before the symptoms. The analyses are in progress and should be completed by the end of the year.

The research was financed by the National Council for Scientific and Technological Development / Department of Science and Technology (CNPq / DECIT), Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (Faperj), National Malaria Program / Ministry of Health, Fiocruz/CGLAB and UFRR.