An overview of malaria epidemiology in the Amazon region from 2003 to 2012 showed the greatest reduction of cases in 2012 when 241,806 cases of malaria were registered, representing a reduction of 60.1% compared to 2005 and 9.1% in relation to 2011 [15]. The malaria cases reduction number observed in Roraima from 2011 to 2013 was also recorded in other Brazilian states of the Amazon Region, mainly in the years 2012 and 2013. This reduction, however, was not homogeneous: the states of Pará, Rondônia and Amazonas presented 69, 40 and 8% of reduction, respectively, in 2013 compared to 2012; meanwhile, in Roraima this reduction rate was 18.64% in 2013 when compared to 2012 [4]. In 2013, the API of 9.89/1000 inhabitants was the lowest identified in the study period. It was the only year in which the Roraima state was classified as low risk for malaria transmission.
Conceivably, this reduction was a result of the actions adopted by the National Programme of Malaria Control (PNCM) of 2005, including: new schedules of P. falciparum treatment involving the use of artemisinin-based combination therapy (ACT) and primaquine; use of long-lasting insecticidal bed nets; supervision in diagnosis stations; quality control and monitoring of diagnosis performance; use of RDTs; detection systems and epidemic alert; the project of expanded access to prevention and control measures against malaria for Vulnerable Populations of Brazilian Amazon in 2009 (sponsored by the Global Fund to Fight AIDS, Tuberculosis and Malaria), and the Project of Municipal Supporters for Malaria Control in 2012; and, strengthening local team skills in epidemiological investigation, aiming to promote a progressive reduction of malaria cases [15, 16].
It is noteworthy that even considering that the PNCM actions in place in Roraima, API increased 211.67% infection risk in the time span 2014 to 2020, diverging from the reduction of malaria cases observed in the rest of Brazil in the same period. In addition, data from the Ministry of Health pointed to a decline of 19.1% from 2017 to 2020 [4]. In fact, the distribution over time of malaria cases in Roraima from 2010 to 2020 presented a significant variation over the decade, although during the same period API has shown a medium degree of infection risk (API 10–49.9/1000 inhabitants). However, after the reduction in the number of malaria cases in 2012 and 2013 in Roraima, the cases increased by 18.13% in 2014, specifically in the DSY areas, due to the return of illegal mining activities, mainly on the banks of the Uraricoera, Mucajaí and Couto de Magalhães rivers. In reality, mining activities on the banks of the Uraricoera river already existed from 1987 to 1989 in such a way that up to 2,003 mining rafts were counted near the indigenous community of Waikás. These mining operations were shut down in 1991 after the conclusion of the indigenous territories’ boundary demarcation. But, in 2010 new gold mining rafts returned to the Uraricoera. Despite the efforts of local leaders, gold miners refused to leave the region, alleging that mining activity was the only source of income for their families. By the end of 2016, 133 open-pit gold-mines were identified in the Yanomami area, and were opened with greater momentum from 2018 [13, 17].
The scenario of increasing malaria cases triggered by illegal gold mining in the indigenous Yanomami areas and the resulting impact on the local health system has established several meetings of teams involved with malaria control in the Roraima DSEIs municipalities and Ministry of Health/SESAI representatives, in an effort to find effective solutions.
In 2018 a proposal of registering gold miners inside Yanomami lands in the SIVEP-Malaria platform was put forward, in order to allow the stratification of transmission data by origin in indigenous areas with or without mining activities, as control actions adopted in each case are distinct. This record from 2019 in Roraima, showed the increase in the number of autochthonous cases of malaria in mining areas. However, the registration of malaria cases from mining locations is far from reality, reinforcing the need for professional training for malaria notifiers, as well as the investigation of the likely source of infection of the reported cases. It is worth noting that the illegality of gold mining activities in Roraima hinders state efforts to control the disease in the municipalities and DSEI-Yanomami, in terms of safety and logistics issues.
The access routes to the mining areas are mainly through the rivers and forest areas of the municipalities of Alto Alegre, Amajari, Mucajaí, Caracaraí, and Iracema, or by plane through clandestine hidden airstrips in rural areas. The API spatial analysis of these municipalities during the study period showed that Amajari and Alto Alegre presented the largest periods under high infection risk. Amajari presented a high infection risk over the whole decade, except for 2017 when it presented a medium risk. Alto Alegre, in turn, was under high risk of infection for seven years, except for 2012 and 2014, when it showed medium risk, and in 2013 low risk.
The pressure of illegal mining is greater in the Yanomami indigenous areas, however, more recently, this activity has also been identified in the Raposa Serra do Sol Indigenous Land, in the DSEI-Leste, located in the municipalities of Normandia, Pacaraima and Uiramutã, between the Tacutu, Maú, Surumu, and Miang rivers and on the Venezuelan border [18]. A survey carried out in 2020 showed the existence of illegal diamond mining in the municipalities of Uiramutã and Pacaraima [13]. During the study period, these municipalities showed a high risk of malaria transmission from 2018, which remained until 2020.
According to the World Health Organization, malaria cases in the Americas fell from 894,000 in 2019 to 653,000 cases in 2020. Part of this reduction was attributed to movement restrictions during the COVID-19 pandemic and to the lack of fuel affecting mining activities. Such restrictions could also have affected access to care and case detection [3]. The malaria scenario in Roraima during the COVID-19 pandemic was different, with a 44% increase of autochthonous malaria cases in 2020 when compared to 2019. Interestingly, in 2020, there was also a 30% increase in mining activities in Yanomami indigenous land, mainly in the Waikas and Kanayanau regions. The new illegal mining centres were located mainly in the channels of the Uraricoera river, which concentrates 52% of the total area of illegal mining in the Yanomami indigenous land. Illegal mining was also identified on the banks of the Parima, Mucajaí, Couto de Magalhães, and Catrimani rivers [17].
Malaria control in the gold mines of Roraima is a major challenge. In addition to the difficulty in controlling the vector, mining is illegal and is carried out in areas of difficult access, making timely diagnosis and treatment considerably difficult [19]. Another problem in mining areas is that people infected with malaria often self-medicate with erratic regimens, often using just a dose called ‘incubator’ to quickly eliminate symptoms and return to mining. These non-curative underdoses favour parasites resistant to anti-malarials [20, 21]. In addition, miners use drugs of dubious quality, such as Artecom® (artemisinin-based medication), which is not registered by a drug regulatory authority or by the WHO prequalified programme and is therefore illegal in French Guiana and neighbouring countries [22].
Malaria control in illegal miners goes beyond the domain of public health, and it is necessary to include other government bodies in the debate on gold mining in indigenous lands, which as in any other economic activity must take principles of sustainability, preservation of biodiversity and guarantee the cultural and social rights of indigenous peoples to ensure social wellbeing and health of indigenous and non-indigenous populations.
In 1961, the Bolivarian Republic of Venezuela (hereinafter called Venezuela) was the first country certified by WHO to eradicate malaria; nevertheless, as of 2012 the country’s situation turned alarmingly. Economic collapse in Venezuela led to a lack of anti-malarial medication and the failure of other control measures, resulting in a rise in case numbers, both in endemic and non-endemic regions, affecting neighbouring countries with imported malaria cases, including infections due to P. falciparum [23]. The economic crisis has driven many people to illegal gold mining, where they contract malaria and spread the disease when returning home. Cases of imported malaria proceeded mainly from Bolivar and Amazonas, Venezuelan states bordering Brazil.
On the Brazilian side, the Pacaraima municipality has a population of 11,667 inhabitants, including the indigenous population. The seat of the municipality, the only non-indigenous area in the municipality, is located at an average altitude of 900 m and has vegetation cover of steppe savannah, thus presenting a negligible risk for malaria transmission. However, the indigenous areas of São Marcos, located alongside highway BR-174, offers favourable environmental conditions for the mosquito vector. Venezuelan immigration has contributed to the recrudescence of autochthonous cases in these native communities because they serve as shelters for refugees when they move to the capital, Boa Vista, along the BR-174, and in 2018 to 2020, the municipality of Pacaraima presented a high risk of malaria infection. The biggest reduction in 2020 can be explained by the Venezuelan border closing during the period of the Covid-19 pandemic. On the other hand, an increase in autochthonous cases, mainly in indigenous localities of DSEI-Leste, located in the municipality of Pacaraima, was recorded.
Indigenous reserves occupy 70% of areas in the municipalities of Normandia, Uiramutã, Alto Alegre, Pacaraima, and Iracema. In these municipalities, malaria infections are concentrated in the indigenous area, with little or no transmission in non-indigenous areas.
The measures of malaria prevention and control in indigenous areas are also a challenge to public health, due among other reasons to environmental changes and to nomadic behaviour and cultural characteristics such as hunting, fishing, farming, and bathing in rivers and streams [5]. Some studies point out that in the Amazon, the risk of indigenous people getting sick from malaria is twice that of non-indigenous people. These studies indicate that in the period 2003 to 2012 the epidemic municipalities were characterized by having indigenous populations, settlements, gold mining, and international borders [6, 15, 24].
Timely diagnosis and treatment have a greater impact on the control of malaria caused by P. falciparum, since P. vivax infections present gametocytes (the infectious mosquito stage) from the first days of infection; in turn, P. falciparum gametocytes are found in the bloodstream only after seven days of infection [5]. Thus, a significant percentage rise of infections due to P. falciparum, reported over the observation period, highlights the lack of access to opportune treatment, mainly in gold miners’ malaria cases. If not timely treated, malaria can evolve to its severe forms, causing hospitalizations and deaths. The percentage of hospitalizations due to malaria, not only in Brazil but also in endemic areas of the world, is directly proportional to the provision of timely diagnosis and adequate treatment.
Plasmodium vivax infections have been increasingly associated with an important, multisystemic impact on individual health, mainly in the presence of co-morbidities [25]. Vivax malaria cases may also develop into more serious forms of the disease, either because of inexperienced outpatient care, late diagnosis, inadequate/incomplete treatment, or even drug resistance [26, 27].
The number of deaths caused by malaria in Roraima can be considered high when compared to national data. While from 2000 to 2017 there was a progressive reduction of deaths nationwide (from 245 to 34), in Roraima 18 deaths caused by malaria were reported in 2018 alone, although from 2010 to 2017 the mortality rate averaged three deaths per year, with up to 24 deaths within a period of eight years. Besides this increase, in 2019 deaths due to malaria in Roraima made up 46% of the total reported for Legal Amazon [4]. These data are probably due to a larger number of imported cases from Venezuela (11 deaths) and the increase of malaria infections in gold mining areas among Brazilians (7 deaths) in 2018. In 2019, 16 deaths, six in Venezuelans and 10 in Brazilians were reported in Roraima. These figures exemplify how difficult is timely diagnosis and treatment in Venezuela and in mining areas.
This study, like any study based on secondary data, may have some limitations related to possible underreporting, incompleteness and inadequate registration.
