Brazil’s Pantanal is one of Earth’s most remarkable places, a vast mosaic of wetlands, grasslands, and forests that explodes with biodiversity. Bigger than England and teeming with life, it is home to the world’s highest density of jaguars, more than 650 types of birds, and numerous species found nowhere else on the planet. 

It’s a unique and stunning landscape that offers incomparable wildlife scenes: caimans by the thousands basking on muddy banks, giant otters weaving through flooded forests, and marsh deer stepping delicately across flooded plains.

But even this Eden has its edge.

Seasonal fires—many related to human action, intentional or otherwise—have grown more intense and frequent, incinerating wildlife and threatening delicate ecosystems. Deforestation in the Pantanal is occurring at an average rate faster than anywhere in Brazil. And controversial hydroelectric projects loom, which scientists warn could fragment one of the most intact wetland systems on Earth.

In this wild and fragile place, as changes disrupt the balance of the Pantanal's unique environment, a new international research collaboration is asking urgent questions: How are diseases now moving between wildlife, livestock, and people here—and what can that teach us about global health?

From the Upper Midwest to the flooded heart of South America

Researchers from the Universidade Católica Dom Bosco (UCDB) in Brazil have partnered with the University of Minnesota’s College of Veterinary Medicine (CVM) and College of Food, Agricultural and Natural Resource Sciences (CFANS). The teams are working together to explore disease ecology in the Pantanal, using innovative tools and local knowledge to better understand how zoonotic diseases (those that can jump between animals and humans) move through ecosystems.

The partnership is co-led by Brazilian veterinarian Heitor Miraglia Herrera, leader of the InsanaHuna research group, which studies the interface between animal, environmental and human health; CVM wildlife epidemiologist Tiffany Wolf and wildlife movement ecologist James Forester (CFANS); along with colleagues from both the University of Minnesota and UCDB.

Herrera’s family has ranched in the Pantanal for generations, and their century-old property now serves as a field research station and hub for ecosystem health research. For many families in the region, their livelihood depends on cattle ranching—an economic foundation increasingly at risk from fire, drought, and other environmental pressures that also threaten the wider ecosystem.

An echo of Yellowstone

The Pantanal might be half a world away, but for researchers, it has striking parallels to the Greater Yellowstone Area (GYA) in the U.S.

Both regions are iconic landscapes where people and nature collide—where cattle graze among wild species and conservation lives alongside livelihoods. And both face a shared threat: the complex, persistent problem of brucellosis.

Caused by bacteria in the Brucella genus, brucellosis affects animals such as cattle, bison, elk, pigs, dogs, and even humans. In animals, it often leads to infertility and miscarriage. In people, it can cause fever, fatigue, and joint pain and can persist for months or even years without treatment.

The U.S. successfully eradicated brucellosis from domestic cattle decades ago, but it still lingers in Yellowstone elk and bison, two species originally exposed to the bacteria from cattle grazing in their native habitat. Until recently, bison were thought to be the source of periodic spillovers back to livestock. But genetic data from whole-genome sequencing has revealed that elk are actually responsible for spillback to cattle.

Now, the Brazilian team is asking similar questions: What role do domestic livestock, feral swine, and free-ranging pampas deer play in brucellosis transmission cycles in the Pantanal? 

Brucellosis can become enzootic, or endemic in animal populations, in large areas where wild animals and livestock share the same habitats, such as the Brazilian Pantanal. In these areas, management approaches have to consider both animal production and biodiversity conservation, including monitoring susceptible wild species.

The team’s current project, then, will evaluate how Brucella infection affects populations of different species of wild and domestic ungulates (hooved mammals) in the Pantanal of Mato Grosso do Sul, using a variety of techniques including bacterial isolation, third-generation genetic sequencing, and assessment of habitat selection, landscape, and environmental variables.

Wildlife, livestock, and a mystery to solve

Brazilian researchers had previously used PCR, a method that detects specific DNA targets, to flag possible Brucella infections. But PCR can’t easily identify unknown species or reveal how the bacteria are spreading, which limits what scientists can do with the data.

That’s where the Minnesota team stepped in.

During their first field expedition to Brazil in June, they used a cutting-edge technology known as nanopore adaptive sequencing to analyze DNA from wildlife and livestock in real-time. Portable and field-ready, this fourth-generation sequencing device can read full genomes in 24 hours, even in the middle of the flooded plains.

Unlike traditional methods that require scientists to have an idea of what they’re looking for, nanopore adaptive sequencing can detect a wide range of pathogens, even unexpected ones. A process called “adaptive sampling” allows researchers to ignore host DNA (like that from deer or cattle) and focus on microbial material, casting a broader net for hidden pathogens. They can also enrich for specific pathogens of interest, like Brucella, ignoring everything else and obtaining much deeper sequencing data that can allow almost full genome sequencing. 

“We knew from what has been learned in the Greater Yellowstone system that we would need to generate a substantial amount of genetic data on any Brucella detected in this system to have any hope of understanding transmission patterns,” Wolf says. “We were very excited to see that nanopore adaptive sequencing allowed us to do just that—having produced sufficient genetic data from samples to cover almost the entire Brucella genome.”

In addition to sequencing pathogens, the team is using GPS collars on pampas deer to collect data on movement, reproduction, and calf survival. These deer, once plentiful in the region, are in decline. Researchers suspect habitat loss or disease may be contributing factors. This work could clarify the role of brucellosis or other threats to the pampas deer population in the Pantanal region.

Science that serves communities, locally and globally

The Pantanal field station, equipped with lodging, labs, livestock handling tools, and deep-rooted community ties, is a vital resource. And while the Minnesota team brings specialized expertise, it’s building on decades of local research and knowledge.

The project is still in a pilot phase. This early work is helping the team test what’s possible—what questions can be answered, what technology works in the field, and what data they’ll need to pursue larger studies. This fall, Forester is scheduled to return to collar more deer and continue sampling.

If successful, the collaboration could become a long-term model for transboundary global health research, with relevance far beyond Brazil. Brucellosis remains a challenge around the world. Learning how it behaves in the Pantanal, where wildlife, livestock, and humans intermingle in ways both similar and unique to the U.S., could lead to better strategies for monitoring and preventing the disease across continents.

These insights will help to shape a broader picture of how diseases move across species—knowledge that’s increasingly vital in a rapidly changing world.