As the world turns its attention to the Amazon in anticipation of COP30—set for November 2025 in Belém, Brazil—a landmark scientific study has brought renewed urgency to the intertwined challenges of environmental degradation and public health. The research, published in Acta Tropica on July 30, 2025, unravels the complex relationship between deforestation and malaria transmission in the Amazon, offering a nuanced perspective that could reshape both disease control and conservation strategies.
Focusing on Cruzeiro do Sul, a municipality in Acre situated along the Juruá River Valley and recognized as a persistent malaria hotspot, scientists conducted a comprehensive investigation that spanned 40 field sites across a gradient of forest cover. This region, emblematic of the broader Legal Amazon, has long struggled with unrelenting malaria outbreaks despite sustained public health efforts.
What did the researchers discover? According to the study, malaria transmission risk peaks in areas where approximately 50% of the native forest has been lost—a scenario described as “intermediate deforestation.” These fragmented landscapes, as explained by the research team, foster increased contact between humans and Anopheles mosquitoes, specifically those of the Nyssorhynchus subgenus, notorious for their role in transmitting the Plasmodium parasites responsible for malaria.
“In our research, we found that the highest risk of malaria transmission occurs when there’s a 50% proportion of native forest near housing, settlements, or population centers. The risk is also high when vegetation is fragmented, allowing greater contact between vectors in the forest and humans. On the other hand, it decreases if deforestation is complete, because the environment becomes inhospitable to the vector, or when the forest is restored to levels above 70%, showing the importance of conservation and restoration,” said Gabriel Laporta, the study’s corresponding author and a biologist at FMABC Medical School University Center, in remarks to Agência FAPESP.
The methodology was as rigorous as it was innovative. Field teams simultaneously collected Anopheles mosquitoes and blood samples from local residents, employing molecular diagnostics to detect infectivity in both vectors and humans. This approach allowed for a detailed landscape epidemiology analysis, revealing that infection rates were highest in regions with intermediate deforestation and considerably lower where forest cover exceeded 70% or had been almost entirely cleared. The findings underscore the protective effects of intact, biodiverse ecosystems and the disruptive impact of complete deforestation on mosquito habitats.
This research builds upon earlier work by Laporta and colleagues, including a 2021 Scientific Reports article that identified two peaks in vector occurrence after settlement establishment: one at 10-12 years and another at 36-38 years. In both instances, landscape changes reduced overall mosquito diversity, allowing Nyssorhynchus darlingi—a particularly efficient vector of Plasmodium vivax—to become dominant. Such ecological shifts further complicate malaria control in the Amazon, where the disease has proven stubbornly persistent.
The implications of these discoveries are profound. As the study notes, the persistent association between deforestation and malaria transmission means that traditional interventions—such as insecticide-treated nets, indoor spraying, and rapid treatment—may not suffice unless coupled with environmental management strategies. “Environmental and public health issues seem far apart, but they’re closely connected. One way to intervene in areas such as those we studied would be to promote sustainable initiatives that provide income for residents. Conserved forests have valuable products, but they tend to be less profitable than opening up the land for pasture or agricultural use. Payment for ecosystem services, through the carbon market, for example, may be an alternative. A conference such as COP30, which brings together government officials and decision-makers, can be an opportunity to discuss how we’ll replace today’s modus operandi,” Laporta commented.
The study is part of a broader initiative funded by the São Paulo Research Foundation (FAPESP), which supports young investigators and doctoral scholars. Over a five-year monitoring period set to conclude in 2027, the project employs geoprocessing modeling and remote sensing to track the incidence of malaria and other parasitic diseases—such as Chagas and cutaneous leishmaniasis—in relation to deforestation and environmental change. By integrating parasite infection data from both mosquitoes and humans, the team aims to provide policy-makers with actionable insights that bridge the gap between public health and ecological stewardship.
Deforestation is hardly the only culprit. The study points to large infrastructure projects—like hydroelectric plants, mining, and urbanization—as additional drivers of disease spread. Climate change, too, is exacerbating the problem by creating more favorable conditions for mosquitoes: rising temperatures, intensified rains, and prolonged droughts all contribute to the expansion of vector habitats and the acceleration of mosquito life cycles. The interplay of these factors, researchers argue, demands adaptive public health strategies that recognize the critical role of landscape management.
The stakes are high. According to Brazil’s Ministry of Health, the Legal Amazon accounted for 138,000 of the nation’s 142,000 malaria cases in 2024. The government’s National Malaria Elimination Plan aims to reduce cases to fewer than 14,000 by 2030 and achieve elimination by 2035—a goal that will require not just medical interventions but also robust conservation efforts. On the global stage, the World Health Organization estimates that malaria caused 263 million cases and nearly 600,000 deaths in 2023, with 95% of fatalities occurring in Africa due to limited access to prevention and treatment.
Preventive measures remain crucial. Individual protections—such as mosquito nets, screens, and repellents—must be combined with collective actions like sanitation, filling vector breeding sites, and improving the living conditions of vulnerable populations. In Brazil, the public health system (Sistema Único de Saúde) provides outpatient care to facilitate early diagnosis and treatment, which is vital in preventing severe complications, including seizures, bleeding, and altered consciousness.
Yet, as this study makes clear, the time has come for a paradigm shift. “The combination of these ecological factors with improved treatment protocols can leverage malaria elimination efforts,” the researchers write. By maintaining biodiversity and supporting sustainable livelihoods—potentially through carbon credit markets and payment for ecosystem services—Amazonian communities can become allies in both conservation and disease control.
The inclusion of health as a thematic focus at COP30 is a recognition that environmental and public health agendas are inseparable. As the Amazon faces mounting pressures from deforestation and climate change, the lessons from Cruzeiro do Sul offer a path forward—one that balances ecological integrity with the well-being of those who call the rainforest home. The world will be watching as leaders, scientists, and local communities come together to forge solutions that are as resilient as the Amazon itself.
