Epidemiological Alert: Highway in Brazil spreads new diseases to humans

By Lucas Ferrante** – special content for Cenarium

The reactivation and paving of the BR-319 highway, connecting Manaus to Porto Velho, have raised concerns among scientists and environmentalists due to the increased risk of infectious disease spread in the Amazon. Earlier this year, researcher Guilherme Becker from Penn State University and I published an alert in Nature, highlighting how BR-319 exposes the world’s largest zoonotic reservoir. Zoonotic spillovers, when diseases transfer from animals to humans, are directly linked to environmental degradation and deforestation, which increase interspecies contact. Epidemiological data published in the Journal of Racial and Ethnic Health Disparities already supported this hypothesis, demonstrating a more than 400% rise in malaria cases in areas affected by deforestation caused by the central stretch of BR-319. This environmental degradation and deforestation, coupled with the expansion of activities like livestock farming, heighten the risks of zoonotic spillovers. This phenomenon was documented in a study published in the scientific journal Regional Environmental Change, led by me with researchers from the National Institute for Amazonian Research (INPA) and the Federal University of Minas Gerais (UFMG). The study highlighted the risk of emerging diseases from the Amazon region.

In October, in a new publication in The Lancet, I pointed out that this highway might not just lead to Manaus but could pave the way for the next pandemic and the emergence of new diseases. Alarmingly, that same month, Judge Flávio Jardim dismissed these concerns as mere theory, maintaining the preliminary license for paving BR-319. It’s important to note that this license failed to meet all the requirements of the environmental licensing process, such as including affected Indigenous communities in public hearings, making it irregular, as reported by the Journal of Racial and Ethnic Health Disparities and highlighted by CENARIUM since 2023.

A week after the judge’s decision, a study published in the renowned journal Nature Medicine confirmed that BR-319 has been propagating new diseases. The article, also from October 2024, revealed that the spread of a new lineage of the Oropouche virus originated in the Amazon region crossed by BR-319. This arbovirus, maintained in transmission cycles among wildlife and vectors like mosquitoes and sandflies, jumped to human populations in the BR-319 region, resulting in over 6,300 confirmed cases since 2022.

The authors noted: “The weakening of environmental governance in Brazil between 2018 and 2022 certainly acted as a catalyst for the advance of deforestation. Accelerated deforestation in the Amacro region coincided with its designation as a special agricultural development zone, the expansion of agribusiness activities reliant on clear-cutting forests, and infrastructure improvements such as BR-319, which connects the capitals of Amazonas and Rondônia and crosses several conservation units and Indigenous lands. While it is challenging to establish direct causality between events, the circumstantial evidence described above points to a potential link between the current Oropouche outbreaks and extrinsic environmental factors that culminate in increased human exposure to pathogens in the Brazilian Amazon.” — Excerpt from a direct translation of the study [from English to Portuguese].

These findings support hypotheses published in Nature and The Lancet that increased mobility and forest degradation caused by BR-319 spread new diseases. However, in Manaus, we observe silence from traditional media and health surveillance authorities. This is unsurprising: during the COVID-19 pandemic, the Health Surveillance Foundation (FVS) denied the onset of a second wave of COVID-19. Epidemiological alerts came from my research group, with the first risk alert issued six months in advance, also in a study I coordinated published in Nature Medicine.

A study published in Preventive Medicine Reports demonstrated how the progression of community transmission of the coronavirus in Manaus led to the Gamma variant, also known as P.1, during the second wave of COVID-19, responsible for two-thirds of COVID-19 deaths in Brazil and other countries. A recent study I coordinated, published in the Journal of Public Health Policy, showed how BR-319 contributed to increased community transmission of SARS-CoV-2 in Amazonas, facilitating the virus’s spread in Indigenous communities. As reported in Science, Indigenous peoples are at higher risk for COVID-19, showing three times greater susceptibility to death than non-Indigenous populations, as highlighted in The Lancet.

Currently, the new lineage of the Oropouche virus, like the Gamma COVID-19 variant, originated in Amazonas and has already spread across Brazil via BR-319, with cases reported as far as Espírito Santo state. In November, the state recorded approximately 500 cases of the disease; today, it reports over 2,400 cases, linked to fetal loss, microcephaly, congenital problems, and deaths. This situation prompted an alert from the U.S. Centers for Disease Control and Prevention (CDC), warning against travel to affected areas. The first cases in Espírito Santo were reported in rural areas in April this year.

Regarding BR-319, the Journal of Public Health Policy study, involving researchers from INPA, the Federal University of Amazonas (UFAM), UFMG, the Federal University of São João del-Rei (UFSJ), the Butantan Institute, and Paulista University (Unip), revealed that contact transmission rates, such as those for coronaviruses, increased by more than 2,000% between 2020 and 2022 for Amazonas, over 1,500% for Porto Velho in Rondônia and Manaus in Amazonas, and over 500% for Humaitá. The study highlights that arguing the highway was opened in the 1970s and no pandemic emerged is fallacious since it was impassable between 1988 and 2015. Only after the repaving license in 2015 did deforestation increase, as shown in a study published in Land Use Policy.

A study I co-authored last year with Nobel Prize winner Philip Martin Fearnside from INPA stated: “Deforestation from the reconstruction of BR-319 is likely to cause the central Amazon to experience climatic anomalies already observed in the ‘deforestation arc,’ further degrading the forest and increasing the risk of a new pandemic emerging in this area. This raises concerns about the extraordinary degradation potential of BR-319 and underscores the importance of the Madeira River as Manaus’s primary route.”

The study concludes: “Warnings about zoonotic spillovers and pandemic risks from environmental degradation and deforestation are often ignored, as was the case with COVID-19 warnings a year before its emergence, identifying coronaviruses in bats in Wuhan, China. Since the Amazon is one of the largest zoonotic reservoirs in the world, a new global health crisis originating here could be even more significant than what occurred in China. The rise of endemic diseases due to environmental degradation in the BR-319 area is a bioindicator of imminent zoonotic risk. These indicators must be considered by environmental agencies deciding on the project’s licensing. The public health environmental risk is one factor contributing to the environmental unfeasibility of this enterprise.”

Since March this year, my team has monitored diseases in the BR-319 region through environmental DNA analyses from water and soil samples collected along the highway. The results will be presented to the Ministry of the Environment (MMA) in January 2025 and are being monitored by the Federal Public Prosecutor’s Office (MPF) to ensure the MMA considers this data.

We must review this highway, which is not just a route to Manaus but a road to the next global pandemic—or a sequence of pandemics. Manaus has a history of ignoring researchers’ warnings, as seen during the second wave of COVID-19 and the risk of zoonotic spillovers. Malaria cases have already risen, as have cases of the new Oropouche virus lineage, which emerged in the BR-319 region due to increased deforestation and traffic. This virus has already spread across Brazil, raising alarming health concerns.

(*) Lucas Ferrante holds a degree in Biological Sciences, as well as a master’s and doctorate in Biology (Ecology). He is the Brazilian researcher with the highest number of publications as the first author in the two leading scientific journals in the world, Science and Nature. Currently, he is a researcher at the University of São Paulo (USP), the Federal University of Amazonas (Ufam), and a collaborating researcher at the Management and Operational Center for the Amazon Protection System (Censipam).
(*) This content is the responsibility of the author.

Translated from Portuguese by Gustô Alves