Changes in the environment and climate, as well as fungicide overuse in agriculture, have driven a rise in fungi capable of infecting people and evading the few drugs designed to fight them.

When the 48-year-old longtime smoker came to Shmuel Shoham, an infectious diseases expert at Johns Hopkins, she was worried about cancer. The woman, who had received a liver transplant decades before, had been coughing and losing weight for months before seeking treatment. The pulmonologist on call biopsied one of the nodules dotting her lungs fearing a tumor. Instead he found Aspergillus, a common fungus—which occurs everywhere from compost piles to carpets to the local flower shop.

“I worry a lot about fungus because of the kind of patients I see,” says Shoham, who treats people with compromised immune systems who are particularly vulnerable to opportunistic microbes like fungi. But lately, fungi have been popping up more often in clinical settings. In India, for example, a perfect storm of respiratory tract injuries, immune suppressing steroid treatments, and uncontrolled diabetes have led to a surge in COVID-19 patients contracting invasive, frequently deadly, black-mold fungal infections. Then there’s Candida auris, a virulent, blood-borne fungal infection which emerged out of nowhere to become a major human pathogen—one that’s resistant to multiple antifungals and that can colonize surfaces for months.

“What we worry about all the time in the fungal world, is fungi’s potential to cause human disease,” says Tom Chiller, a medical epidemiologist and chief of the Mycotic Diseases Branch at the Centers for Disease Control and Prevention. “There’s a lot of stuff out there we don’t even understand.”

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