• Healthy forests in protected Indigenous territories could help reduce the risk of certain illnesses for humans, a new study shows.
• Different factors influence how effective Indigenous territories are at protecting health, including whether a territory has legal protected status and the type of landscape surrounding it.
• Researchers found that Indigenous territories can effectively reduce the risk of vector-borne or zoonotic diseases if they’re located in municipalities with at least 40% forest cover.
• The study used a data set of respiratory, cardiovascular, vector-borne and zoonotic diseases recorded across the Amazon region between 2001 and 2019 to understand how pollution from forest fires, forest cover and fragmentation, and Indigenous territories impacted the risk from 21 different diseases.

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Indigenous territories are widely recognized as vital for conserving the environment and biodiversity, but far less is known about their role in protecting human health.

Only recently have researchers begun to fill in this knowledge gap and investigate how the protection of these areas can provide health benefits as well as ecosystem services. Now, a new paper analyzing the relationship between Indigenous territories and the occurrence of 21 diseases in the Amazon biome over 20 years suggests that healthy forests on protected Indigenous territories can help reduce disease incidence and risks to human health.

“Indigenous forests act as a sort of shield for health,” said study lead author Júlia Rodrigues Barreto, a postdoctoral researcher at the University of São Paulo in Brazil. Published in Communications Earth & Environment, the study is the first of its kind to look at all nine Amazonian countries. Its main contribution, according to Barreto, is to convey the importance of guaranteeing land rights for Indigenous peoples across the Amazon.

Indigenous village of the Huni Kuin people in Jordão, Acre. Indigenous territories with secure land rights not only reduce deforestation inside their lands in the Brazilian Amazon, but also lead to higher secondary forest growth on previously deforested areas. Image by AgniBa via Wikimedia Commons (CC BY-SA 4.0).

Barreto and her colleagues looked at how Indigenous territories, depending on their legal status and landscape characteristics, could influence the incidence of fire-related illnesses, as well as vector-borne and zoonotic diseases — those transmitted by insect bites or passed on from animals. Previous research has found that protecting Indigenous territories in the Brazilian Amazon could help avoid 15 million cases of cardiovascular and respiratory diseases every year, saving around $2 billion in health costs.

Between 2001 and 2019, more than 28.4 million cases of 21 different diseases were recorded across municipalities in the Amazon biome, according to a comprehensive new data set compiled by the study’s authors. The data cover 15 cardiovascular and respiratory diseases related to smoke from forest fires, and six vector-borne and zoonotic diseases, including malaria, Chagas disease and hantavirus. Around 80% of the recorded cases were fire-related illnesses, primarily respiratory.

Researchers analyzed the data against records of fires and smoke pollution; forest cover and fragmentation between 2001 and 2019; and boundaries of Indigenous territories, both legally protected and unrecognized as of 2023. While the findings are complex, they show that municipalities that host legally protected Indigenous lands could have a lower risk of illness.

The extent of forest cover plays a key part in this. Researchers found that to effectively reduce the risk of vector-borne or zoonotic diseases, Indigenous territories need to be located in a municipality with at least 40% forest cover. For fire-related diseases, Indigenous territories can help mitigate the impacts of fine particulate matter in municipalities where the forest cover is higher, more than 45%.

The study’s data set doesn’t allow for comprehensive analysis of the overall evolution of zoonotic and vector-borne diseases, said study co-author Paula Ribeiro Prist, senior program coordinator for forests and grasslands at the IUCN, the global nature conservation authority. But broadly, these illnesses have increased since monitoring began, and deforestation has played a big role in their rise. Clearing trees alters local biodiversity to the benefit of stronger species that can transmit pathogens that are harmful to humans. Deforested areas are also more likely to have a greater human presence, leading to a higher outbreak risk.

Deforestation for agriculture in the Sepahua River watershed, Peru. Credit: © Jason Houston/Upper Amazon Conservancy.

The quality of the forest is important, Barreto said, with a fragmented forest being less effective at shielding the human population from health risks. Deforestation fragments forests into smaller patches and expands forest edges, transition areas between forested and nonforested ecosystems; these can bring people into closer contact with wildlife, increasing the risk of diseases spreading.

“When we deforest too much or fragment areas of native vegetation outside of these territories, this leads to an increase in illnesses,” Prist said.

The link between deforestation and cardiovascular and respiratory problems is less clear, although high amounts of small-sized pollution particles released into the atmosphere by forest fires increased the risk of these diseases, the study found. Deforested areas have a lower capacity to absorb these pollutants.

Between 1985 and 2020, 74.6 million hectares (184 million acres) of native vegetation were cleared across the Amazon, equivalent to 9.6% of the rainforest’s total area, according to MapBiomas, a multidisciplinary mapping initiative.

But most deforestation takes place outside of Indigenous lands. Over the same period, Indigenous territories in the Amazon lost 2.9 million hectares (7.2 million acres) of native vegetation, or 1.2% of their total area, according to MapBiomas.

The situation is similar with forest fires. More than 50 million hectares (124 million acres) of the Amazon Rainforest burned between 2001 and 2019, according to data used by the study. Nearly 90% of the fires occurred outside of Indigenous territories.

A stretch of the Amazon Rainforest in Pará, Brazil, after a megafire in November 2023. Image courtesy of Marizilda Cruppe/Greenpeace.

“When we start to understand that Indigenous territories have better conservation results than normal protected areas, then we start to create the hypothesis that they can also be very good to maintain or restore these [ecosystem] services for human health,” Prist told Mongabay.

Protecting Indigenous land is primordial

Indigenous lands are more likely to provide health benefits to people if they are legally recognized, the study found.

“The legal status of Indigenous territories (ITs) seemed to play a critical role in the potential of ITs to minimize disease incidence, with unrecognized ITs boosting especially fire-related incidence,” the researchers wrote. They hypothesize this is because legally protected Indigenous territories are less likely to be used for unsustainable activities like large-scale farming or logging.

“It is truly important to give land rights over these territories to Indigenous people, not only because they should have this legal ancestral right, but also because they are providing a service for the entire community,” Prist said.

Toya Manchineri, general coordinator of COIAB, an umbrella organization for Indigenous groups in the Brazilian Amazon, said the study’s results are not surprising. “Our people have lived in the forest for a very long time and Indigenous people never suffered from casualties related to illnesses from living in the territory — until first contact [with outsiders],” he told Mongabay by phone.

Securing land rights is the main demand of movements like COIAB in Brazil, but legal protections for Indigenous territories vary from country to country across the Amazon Basin. Colombia, for example, has made strides in guaranteeing not only Indigenous people’s right to occupy their land, but also their governance over these territories. At the other end are Guyana and Suriname, which have incipient legal frameworks for this, according to Carla Cardenas, Latin America program officer for the Rights and Resources Initiative, a coalition of organizations advancing native land rights globally.

Indigenous members of the Kanamari Territorial Surveillance group are seen during a search for illegal deforestation in the middle Javari River region, in the Vale do Javari Indigenous Land, Amazonas, Brazil. March, 2023. Image courtesy of Bruno Kelly/Amazônia Real (CC BY-NC-ND 2.0).

“It’s not only about land tenure, but also about governments making the commitment to not award concession rights for extractive activities in those territories inhabited by Indigenous people,” Cardenas told Mongabay in a written exchange.

“There are still tens of millions of hectares that require [legal] recognition in the region,” she said, adding that it’s hard to know the exact number.

Cardenas said she would like to see governments implement strong land protection policies within the next five to 10 years to avoid further forest and biodiversity loss. She highlighted plans to launch an Intergovernmental Land Tenure Commitment at the upcoming COP30 climate summit taking place in Brazil this November.

The Indigenous movement has expectations of COP30, Manchineri said. “We want the Amazon Basin countries to negotiate and include in the COP’s final declaration a commitment recognizing the demarcation of Indigenous lands as a climate policy,” he said.

The study’s authors say they hope their work will encourage this kind of progress — and also challenge widely held misconceptions of the rainforest as a hotbed of disease.

“Lots of people think you have a high risk of catching a disease when you go to forested areas, and we’re trying to prove the contrary,” Prist said. “It’s actually essential to conserve [the Amazon] to stay healthy and reduce health risks.”

Citations:

Barreto, J. R., Palmeirim, A. F., Sangermano, F., Carrasco-Rueda, F., De Thoisy, B., González-Chaves, A., … Prist, P. R. (2025). Indigenous Territories can safeguard human health depending on the landscape structure and legal status. Communications Earth & Environment, 6(1), 719. doi:10.1038/s43247-025-02620-7

Prist, P. R., Sangermano, F., Bailey, A., Bugni, V., Villalobos-Segura, M. D., Pimiento-Quiroga, N., … Zambrana-Torrelio, C. (2023). Protecting Brazilian Amazon Indigenous territories reduces atmospheric particulates and avoids associated health impacts and costs. Communications Earth & Environment, 4(1), 34. doi:10.1038/s43247-023-00704-w

Barreto, J. R., Sangermano, F., Palmeirim, A. F., Carrasco-Rueda, F., De Thoisy, B., González-Chaves, A., … Prist, P. R. (2025). A Pan-Amazonian dataset integrating 20 years of respiratory, cardiovascular, zoonotic and vector-borne disease cases and landscape changes. Scientific Data, 12(1). doi:10.1038/s41597-025-05656-8

Banner image: Waorani leader Nemonte Nenquimo with elders and community leaders in their territory in the Ecuadorian Amazon. Nenquimo is a long-time defender of the Amazon Rainforest. Image by Nico Kingman, Amazon Frontlines.

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