Climate Denial Crock of the Week

Fungus infections are limited because many fungal organisms cannot survive in warm blooded mammals like humans. But what if, HBO’s “The Last of Us” series asked, what if climate were to warm a few degrees, and fungi adapted to warmer temperatures, and found there way to infect more human beings…?

Washington Post:

A deadly and highly drug resistant fungus is spreading at “an alarming rate” in long-term care hospitals and other health facilities caring for very sick people, the Centers for Disease Control and Prevention announced Monday.

Fungal infections from the yeast strain known as Candida auris tripled nationally from 476 in 2019 to 1,471 in 2021, according to CDC data. Cases where a person carries the fungus but is not infected nearly quadrupled from 1,077 to 4,040 in the same period. Preliminary data suggests the numbers have continued to rise.

Scientists believe the fungus is not a threat to healthy people whose immune systems can fight it off. But it poses a danger to medically fragile people, including nursing home patients on ventilators and cancer patients on chemotherapy. Between 30 to 70 percent of hospitalized people who develop bloodstream infections are estimated to die.
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The fungus has now been detected in more than half the states, with 17 states identifying their first case between 2019 and 2021. Most spread has occurred in long-term acute care hospitals and skilled-nursing facilities, where patients are more likely to be on ventilators, the CDC says. Case counts are probably an underestimate because screening requires specialized equipment and is conducted unevenly across the United States.

Candida can cause fatal infections in the bloodstream, heart and brain. The CDC does not track how many people died, and it can be difficult to discern cause of death when the patients at highest risk are often already fighting for their lives.

The emergence of the fungus, detected more than a decade ago in India, South Africa and South America, has perplexed researchers.

Fungi often cannot withstand the temperature of the human body, but one leading theory posits that Candida is now capable of doing so because it has evolved to survive in a warming world.

“This is how climate change or global warming can bring diseases because those in the environment have to adapt to survive and then have the capacity to survive in humans,” said Arturo Casadevall, a microbiologist at Johns Hopkins Bloomberg School of Public Health who has studied the fungus.

That has eerie parallels to the HBO drama “The Last of Us,” where the real-life cordyceps fungus that creates “zombie ants” adapts to a warming climate and infects humans, unleashing a zombie apocalypse.

Experts credit the show for generating interest in fungal infections that were often overshadowed by viruses and bacteria as the pathogens gripping public attention. Despite its deadly potential, the CDC says the spread of Candida can be stopped if hospitals emphasize surveillance,hand hygiene and deep cleaning with the proper disinfectants.

Lyman offered further reassurance: “We are glad to report it does not cause people to turn into zombies.”

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Yet.

Washington Post:

Fungi are one the six kingdoms of life. We often picture them as mushrooms, yeasts, lichen — or sometimes even athlete’s foot. They appear like plants but don’t make their own food. They can gain energy and nutrients by feeding on living hosts, decomposing dead organic matter or by living harmlessly with other organisms.

They may seem like a minor nuisance to the average healthy human, but the kingdom attacks insects and plants in horrifying ways. One type of fungus, for example, eats away at a cicada’s butt and manipulates its wings to attract mates, spreading the fungus like a STD. The particular fungus that inspired the video game and show, called cordyceps — sometimes referred to as the zombie-ant fungus — causes insects to perch on a branch until the fungus bursts out of its body and releases spores.

People, however, generally don’t experience such graphic, mind-bending encounters with fungi (we’ll discuss LSD and magic mushrooms later). Most fungi don’t infect people because they can’t withstand our warm body temperature or immune system. Between 1.5 to 5 million fungus species may exist in the world, but only a few hundred can make people sick — mostly immunocompromised people, who don’t have a full-strength immune system to fight them off.

In the opening scene of “The Last of Us,” fictional epidemiologist Dr. Neuman challenges these long accepted behaviors of fungi — what if a fungus, say the zombie-ant fungus, could adapt to warmer temperatures and grow in seemingly healthy people? Cue the eerie theme music.

Fungi have been afflicting plants, reptiles and other organisms for millennia. When a giant asteroid hit Earth 66 million years ago, infectious-disease researcher Arturo Casadevall thinks it was a fungal bloom that partly contributed to the decline of reptiles and plants. The post-calamity environment — with loads of decaying vegetation, darkness and global cooling — likely favored the growth of fungus, which helped wipe out coldblooded animals. Small mammals, who were able to regulate their body temperature, were able to better fend off fungal diseases.

Yet over the past few years, Casadevall has been investigating how climate change could bring new fungal infections to mammals, including people.

“Fungi will adapt to warmer climates by developing greater heat tolerance,” said Casadevall, who is a microbiologist specializing in fungal diseases at Johns Hopkins Bloomberg School of Public Health. “Some will then be able to grow at human temperatures and cause new fungal diseases that we have not seen before.”

For instance, Hughes explains, some fungi could adapt by altering the expression of different proteins that allow them to withstand higher heat. A fungus could also increase their melanin, which would allow them to withstand hotter, drier climates.

“It’s either you adapt to the changing climate, or you go extinct,” said Hughes, who is a professor of global food security at Penn State.

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Indeed.