A new study on the mysterious origins of a deadly fungal infection that seemed to have simultaneously emerged in far-flung corners of the globe finds that global warming may be to blame.
Candida auris, a fungus that can kill anyone who comes into close contact with a carrier, was first identified in 2009 in a Japanese patient with an ear infection. It then started showing up in hospitals in Asia, Africa and South America in patients without a clear link — and no one could figure out why.
“The greatest mystery is how you end up with the same fungal species emerging in three different continents at roughly the same time when they are genetically different,” says Dr. Arturo Casadevall, chair of the molecular microbiology and immunology department at the Johns Hopkins Bloomberg School of Public Health. He’s also the lead author of the new Candida auris study, published Tuesday in the journal mBio.
In researching Candida auris, Casadevall’s team looked at close relatives of the fungus. They noticed the majority of them cannot survive in the warm temperatures of the human body, leading them to believe that this fungus may have adapted to higher temperatures.
The majority of fungi grow well in ambient temperatures but only a small percentage can tolerate our body temperature. The concern is that the higher ambient temperatures caused by global warming will eventually lead some kinds of fungus to breach the thermal restriction zone, what Casadevall explains is a zone that is so hot that it typically keeps most fungal species off our body. Without those defenses working, Candida auris and other fungal species that adapt to higher temperatures can infect and possibly kill humans.
So far, Candida auris infections have been reported in more than 30 countries, including India, South Africa and Russia. Over one-third of patients who carry the often drug-resistant disease die, according to the Centers for Disease Control and Prevention (CDC). The disease is still rare in the U.S, with only about 680 confirmed cases nationwide, the CDC says. There have been at least 336 cases in New York, 180 in Illinois and 124 in New Jersey.
Still, experts are worried about Candida auris. It can be difficult to detect, because it often occurs in patients who are already sick from other infections, according to the CDC. Its symptoms include fever and chills that don’t respond to regular antibiotic treatment. People with already-compromised immune systems are especially vulnerable, while hospital outbreaks have led to both confusion and secrecy. Governments across the country and world have often been cautious about creating panic, choosing not to explicitly publicize such incidents.
The fungus is especially alarming to health workers, who may fear for their own safety when treating the illness. They don’t want to catch the infectious disease or transfer it onto another patient. Last May, an elderly man at a Brooklyn hospital who was there for abdominal surgery was infected with Candida auris and died 90 days later. Eliminating all traces of the fungus from his contaminated room was so difficult that “the hospital needed special cleaning equipment and had to rip out some of the ceiling and floor tiles,” the New York Times reports.
Further frightening experts: most known strains of Candida auris have been resistant to at least one of three drug classes used to treat fungal infections. More than one-third of strains were resistant to two, and some appeared to be resistant to all three, according to the CDC.
Casadevall says his results are a sign that humanity may be about to face other new diseases also caused by fungi adapting to warmer climates. Further research, he says, should help us better understand where Candida auris came from and, hopefully, how we might fight it. “How are we going to prepare ourselves?,” he asks. “We’re putting this story together now, 10 years after it happened.”