The battle against the fungal apocalypse is just beginning

Maryn McKenna

Fungal infections are rising worldwide and climate change may be to blame. Medicine isn’t ready

In February, A dermatologist in New York City contacted the state’s health department about two female patients, ages 28 and 47, who were not related but suffered from the same troubling problem. They had ringworm, a scaly, crusty, disfiguring rash covering large portions of their bodies. Ringworm sounds like a parasite, but it is caused by a fungus—and in both cases, the fungus was a species that had never been recorded in the US. It was also severely drug-resistant, requiring treatment with several types of antifungals for weeks.

Then, in March, some of those same CDC investigators reported that a fungus they had been tracking—Candida auris, an extremely drug-resistant yeast that invades health care facilities and kills two-thirds of the people infected with it—had risen to more than 10,000 cases since it was identified in the US in 2016, tripling in just two years.

In April, the Michigan Department of Health and Human Services rushed to investigate cases of a fungal infection called blastomycosis centered on a paper mill, an outbreak that would grow to 118 people, the largest ever recorded.

And in May, US and Mexican health authorities jointly rang an alarm over cases of meningitis, caused by the fungus Fusarium solani, which seemed to have spread to more than 150 clinic patients via contaminated anesthesia products. By mid-August, 12 people had died.

All of those outbreaks are different: in size, in pathogen, in location, and the people they affected. But what links them is that they were all caused by fungi—and to the small cadre of researchers who keep track of such things, that is worrisome

The question is: Why? There may be multiple answers. More people are living longer with chronic illnesses, and their impaired immune systems make them vulnerable. But the problem isn’t only that fungal illnesses are more frequent; it is also that new pathogens are emerging and existing ones are claiming new territory. When experts try to imagine what could exert such widespread influence, they land on the possibility that the problem is climate change.

“Speculative as it is, it's entirely possible that if you have an environmental organism,...you only need a very small change in the surface temperature or the air temperature to.....allow it to proliferate,” says Neil Stone, a physician and fungal infections lead at University College London Hospitals. “And it's that plausibility, and the lack of any alternative explanation, which makes it believable as a hypothesis.”

For this argument, C. auris is the leading piece of evidence. The rogue yeast was first identified in 2009 in a single patient in Japan, but within just a few years, it bloomed on several continents.

Genetic analyses showed the organism had not spread from one continent to others, but emerged simultaneously on each. It also behaved strikingly differently from most yeasts, gaining the abilities to pass from person to person and to thrive on cool inorganic surfaces such as plastic and metal—while collecting an array of resistance factors that protect it from almost all antifungal drugs.

At the height of the Covid pandemic, India experienced tens of thousands of cases of mucormycosis, commonly called “black fungus,” which ate away at the faces and airways of people made vulnerable by having diabetes or taking steroids.

In California, diagnosis of coccidioidomycosis (also called Valley fever) rose 800 percent between 2000 and 2018.

And new species are affecting humans for the first time

In 2018, a team of researchers from the US and Canada identified four people, two from each country, who had been infected by a newly identified genus, Emergomyces. Two of the four died. (The fungus got its name because it is “emerging” into the human world.) Subsequently, a multinational team identified five species in that newly-named genus that are causing infections all over the world, most severely in Africa.

Fungi are on the move

Last April, a research group from the Washington University School of Medicine in St. Louis examined the expected geographic range in the US of what are usually called the “endemic fungi,” ones that flourish only within specific areas.

Using Medicare data from more than 45 million seniors who sought health care between 2007 and 2016, the group discovered that the historically documented range of these fungi is wildly out of step with where they are actually causing infections now.

Researchers who are paying attention to rising fungal problems make a final point about them: We’re not seeing more cases because we’ve gotten better at finding them. Tests and devices to detect fungi, especially within patients, haven’t undergone a sudden improvement.