The Last of Us, adapted to television from the immensely popular and critically praised video game series of the same name, reveals a dystopian world in which Cordyceps – a heat-adapted fungus that exists in the real world – takes over humans and turns them into zombies.
“That’s exactly the sort of thing I’m talking about – minus the zombie part!” pointed out study co-author Asiya Gusa from the Duke School of Medicine in the US.
While there is no immediate threat of humans transmitting fungal infections to each other, scientists warned rising global temperatures may cause microbes to change how they act on humans during infection.
“Rising global temperatures and climate change are predicted to increase fungal diseases in plants and mammals,” they wrote in the study.
Fungi like Candida and Cryptococcus have been known to infect and kill people with compromised immunity, but a vast majority of these microbes have not been able to fare well in the heat of healthy bodies.
In the new study, scientists found that raised temperatures led to a pathogenic fungus known as Cryptococcus deneoformans to increase the number of its genetic changes that might lead to higher heat resistance, and likely also develop increased disease-causing potential in humans.
Out now in PNAS: Genome-wide analysis of heat stress-stimulated transposon mobility in the human fungal pathogen Cryptococcus deneoformans.
By Asiya Gusa, Vikas Yadav, Joe Heitman, Sue Jinks-Robertson & colleagues. @DukeHeitman @PNASNewshttps://t.co/UFnD403dZo
— Nature Microbiology (@NatureMicrobiol) January 26, 2023
Researchers found that with increased surrounding temperatures, parts of the fungi’s genome that contribute to its adaptation to the environment and during an infection can undergo changes.
“This could happen even faster because heat stress speeds up the number of mutations occurring,” Dr Gusa said.
Scientists found that in 800 generations of growth in laboratory medium, the rate of some mutations were five times higher in fungi raised at body temperature, compared to those raised at 30C.
They said the added challenges of surviving in animals with immune responses and other stressors may drive these parts of the fungi’s genome to be even more active.
“This is a fascinating study, which shows how increasing global temperature may affect the fungal evolution in unpredictable directions,” said Arturo Casadevall, another author of the study from Johns Hopkins University in the US.
“As the world warms, transposons [DNA elements that can change position within a genome] in soil fungi like Cryptococcus neoformans could become more mobile and increase genomic changes in ways that could enhance virulence and drug resistance. One more thing to worry about with global warming!” Dr Casadevall said.
In further studies, scientists hope to study pathogens from human patients who have had a relapsing fungal infection.
“We know that these infections can persist and then come back with potential genetic changes,” Dr Gusa said.
“These kinds of stress-stimulated changes may contribute to the evolution of pathogenic traits in fungi both in the environment and during infection. They may be evolving faster than we expected,” he added.
“And they currently do it and have been doing it forever. There are some remarkable documentaries that you can watch that are quite terrifying.”