From mushrooms to molds, fungal life on this planet is often overlooked - but has a big impact. In this series, we dive into fungal research across Duke, a growing area of strength for the university.
Heat is not just an environmental issue. As the planet warms, rising temperatures are causing living organisms to adapt in ways that may have serious consequences for human health.
At Duke University, two researchers are studying what happens when heat changes fungi at the most fundamental level and whether those changes increase the likelihood of human infection.
Assistant research professor Erica Washington and assistant professor Asiya Gusa focus on how fungi respond to heat, from the inside out. Their work asks questions driven by climate change: Are fungi learning to survive temperatures that once killed them? And if environmental fungi become better at handling heat, does that make it easier for them to survive inside the human body?
Their research is made possible in large part by Duke's status as a global leader in fungal science . Decades of work by researchers, funded in large part by the federal government, has built the infrastructure for studying fungal disease, from patient‑derived samples to genetic tools and animal models.
"There's just so much history of knowledge," Washington says, describing a culture where ideas, strains and expertise are shared across labs. Gusa echoes her point, describing Duke as a place where interdisciplinary collaboration enables the study of fungi not only as pathogens but also as organisms being shaped by their environments.
The Fungi We Breathe Every Day
Both researchers, who work in the Molecular Genetics and Microbiology Department at the Duke University School of Medicine , study Cryptococcus, a microscopic fungus that lives naturally in soil and around trees. Its spores float invisibly through the air, so exposure is constant.
"Most people are exposed to these fungal pathogens," Washington, a Duke Science and Technology Scholar , says. "They're in the air … and most people who are immunocompetent can clear them."
For healthy people, that's usually the end of the story. But for individuals with weakened immune systems, such as organ transplant recipients, people undergoing cancer treatment, or people living with HIV, Cryptococcus can cause severe and sometimes fatal infections in the lungs or brain. Heat plays a critical role in determining whether such infections occur.
The human body's temperature of about 98.6 Fahrenheit is one of the strongest natural barriers against fungal disease.
"High body temperature does serve as a deterrent against a lot of fungal infections," says Gusa. Most environmental fungi evolved to survive cool soil, shade and plant matter, not the warmth of a human body.
That's why fungal diseases are less common than bacterial or viral infections, and why they overwhelmingly affect people whose immune systems are already compromised. But climate change is beginning to challenge that.
As environmental temperatures rise and heat waves become more frequent, fungi are increasingly exposed to conditions that mirror those inside the human body. That exposure raises a troubling possibility: Fungi may be adapting to heat in the environment in ways that also prepare them to survive in humans.
"'The Last of Us' video game and HBO series were important pop-culture touchpoints that awakened many people to the potential dangers of heat-adapted fungi and the rise in fungal disease," says Gusa.
When Heat Drives Genetic Change
In Gusa's lab, fungi are exposed to temperatures similar to those of the human body to study how they respond to stress. "Heat stress at human body temperature represents a really strong environmental stressor that they have to overcome," she explains.
Gusa wanted to know whether heat kills fungi or whether it forces them to change.
"What we were looking at is how that exposure to high temperature affects their ability to mutate or make changes that might enable them to survive better," she says.
What her lab discovered was unexpected. Under heat stress, tiny pieces of DNA within the fungal genome, often called "jumping genes," become much more active. "We found that these small pieces of mobile DNA, called jumping genes or transposons, move more frequently in the genome of Cryptococcus at high temperature," Gusa says.
In plain terms, the fungi's genetic instructions are being rearranged under pressure. These jumping genes can land in the middle of important genes, disrupt normal function, or change how much of a gene is turned on or off.
In at least two cases in the lab, those genetic changes helped the fungus grow better at high temperatures. "That's somewhat alarming," she says.
What scientists still don't know is whether heat adaptation also makes fungi more capable of causing disease. "Everyone kind of assumes that if a fungus grows better at body temperature, it's more disease‑causing," Gusa says. "But we don't actually know that."
Sugar That Keeps Fungi Alive
While Gusa investigates how heat reshapes fungal DNA, Erica Washington studies how fungi survive heat in real time .
"There are many mechanisms that fungi use to handle heat," Washington says. "And one in particular that we're really interested in … is that they make this sugar called trehalose."
Trehalose acts like a protective buffer inside fungal cells.
When heat threatens to damage proteins or the cell membrane, this sugar stabilizes those structures and keeps the cell intact. Without it, the fungus cannot survive heat stress.
To infect a human, fungi must tolerate body temperature. "If the fungi can't make trehalose, they can't survive at human body temperature," she says.
Washington's lab is studying the enzymes fungi use to make trehalose, searching for ways to block that process with drugs. It is an early-stage, basic research project, but it's a step toward developing new antifungal treatments in a field where drug options are limited.
"We're really interested in studying trehalose biosynthesis as an antifungal drug target," Washington says. "What it leads to is saving lives."
Climate Change as a Training Ground
Both researchers see climate change as an active force accelerating fungi's evolution. Hotter temperatures tend to favor fungi that can tolerate and survive heat.
"What this is doing is training fungi to also be able to survive in the human body," Washington says.
There is already a real‑world warning sign. Washington points to Candida auris, a heat‑tolerant, drug‑resistant fungus first identified in 2009 that has since spread across continents and caused deadly outbreaks in hospitals.
To better understand how extreme weather contributes to fungal spread, Washington and Gusa collaborate with engineers and environmental scientists at Duke.
After Hurricane Helene caused flooding in North Carolina, they collected fungi from damaged buildings and surrounding areas. Gusa's lab identified the species present, while Washington's lab examined how those fungi might affect human health, particularly for people returning to flooded homes.
Neither researcher predicts a fungal apocalypse, like the one depicted in "The Last of Us". Most fungal diseases are not spread person-to-person, and the risk to healthy individuals remains low. Still, fungal infections are frequently misdiagnosed, underreported, and deadly when treatment is delayed.
At Duke, the depth of fungal expertise enables study of these risks from every angle, including molecular biology, medicine, engineering, and climate science.
"Securing funding is mission-critical so that we can continue to answer questions and seek solutions to fungal threats," says Gusa.
Learn more about how federal funding supports life-changing research at Duke Research Saves Lives .
