A deadly fungus is running rampant through American hospitals and the number of cases is rising at “an alarming rate,” the Centers for Disease Control and Prevention said Monday. After first being detected in the U.S. in 2016, infections from the yeast strain known as Candida auris almost doubled in 2021 alone, with 756 cases seen across the U.S. in 2020 and 1,471 recorded a year later. The 2021 figure is a three-fold rise from 2019’s tally of 476. The drug-resistant fungus is not thought to pose a major risk to healthy people, but can be extremely threatening to clinically vulnerable people, including nursing home patients on ventilators and cancer patients receiving chemotherapy. “If [the fungi] get into a hospital, they are very difficult to control and get out,” William Schaffner, a Professor of Medicine in the Infectious Diseases division of Vanderbilt University Medical Center, told the Washington Post. “They can persist, smoldering, causing infections for a considerable period of time despite the best efforts of the infection control team and everyone else in the hospital.”