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#doomedHow the rise of C. auris was inevitable | Live Sciencehttps://www.livescience.com/planet-earth/microbiology/the-most-critically-harmful-fungi-to-humans-how-the-rise-of-c-auris-was-inevitableFifteen years ago, scientists discovered a new species of deadly, drug-resistant fungus: Candida auris. It is now considered one of the most dangerous fungal pathogens on Earth. In this excerpt from "What if Fungi Win?" (Johns Hopkins University Press, 2024), author Arturo Casadevall looks at the rise of this deadly fungus, which could be the first to have emerged as a result of climate change.
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And C. auris laid low for a while, remaining an obscure unknown yeast in most parts of the planet — until it was found in hospitalized patients in all corners of the world, at roughly the same time. Strikingly, between 2012 and 2015, doctors in South Africa, Venezuela and on the Indian subcontinent simultaneously reported treating patients severely ill with what turned out to be C. auris infections (remember, no one had heard of this fungal species a few years earlier).
With no contact or commonalities between them, these C. auris cases had appeared independently on three different continents, with each fungus genetically distinct from the others.
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It quickly became clear that this fungus was remarkably resistant to treatment. More than one in three patients with invasive C. auris infections in their blood were dying. In hospitals where this invasive fungal disease had been nonexistent, it was now a significant cause of death.
To this day, C. auris remains mostly resistant to the antifungal treatments we have at our disposal, so once patients (and hospitals) become infected, it's nearly impossible to get rid of. Usually, doctors diagnose fungal infections after ruling out other sources, say, when a hospitalized patient has a fever that doesn't go away after treatment with antibiotics. Blood tests will likely indicate high white blood cell counts, another sign of an infection, but doctors often can't tell what type of microbe is doing the damage — or necessarily know how to treat it.
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It could do this because, as doctors would learn, it can colonize human skin, last for weeks on surfaces and tolerate heavy-duty hospital disinfectants. Some hospitals have reported finding C. auris spores lingering in hospital rooms long after a patient was discharged or died, even after other fungal species have been eliminated by cleaning agents. C. auris didn't just stay overseas.
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Within a decade of it being identified, C. auris was killing people in 40 countries on six continents. We don't have exact numbers, as many cases go unreported or unrecognized, but the figure is certainly in the thousands. In the US alone, there were more than 2,000 infections in 27 states
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Body temperature may have long protected us from fungus, but we would quickly learn that C. auris was different. Unlike most of its fungal cousins, it can grow at temperatures as high as 42 degrees Celsius (107.6 degrees Fahrenheit).
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"Global warming could have a significant effect on fungal populations," we wrote. "First, a warmer climate could change the distribution of heat-tolerant and susceptible species by favoring those that are more thermotolerant, and by creating conditions for more environmental fungi to spread and enter into closer contact with human populations. Second, under strong selective pressure, the prevalence of species adapted to heat tolerance may increase."
It wasn't a matter of if fungi would adapt to temperatures high enough that they could threaten humans, we warned, but when.