Brain Fungus With 70% Death Rate Rising Across America

A brain fungus that kills up to 70 percent of the people it infects is being detected at sharply rising rates across the United States, according to a new report from the Centers for Disease Control and Prevention. Detections of the organism — a dark, melanin-rich mold called Cladophialophora bantiana — nearly quadrupled between 2023 and 2025, researchers said. The findings, published in the CDC's Morbidity and Mortality Weekly Report, drew on testing at a specialized University of Washington microbiology laboratory in Seattle. Between January 2009 and July 2026, the lab confirmed 48 infections and one probable case across 21 states and Washington, D.C. The median patient age was 68. For years the brain fungus was vanishingly rare: the lab detected just one to five cases annually from 2009 through 2023. Then the numbers climbed to eight in 2024 and 14 in 2025 — a fourfold jump in two years that prompted the CDC brain fungus report and calls for national tracking of the infection. ## Brain Fungus Carries a 60–70 Percent Death Rate The mold typically heads for the brain, where it forms abscesses — pockets of dead tissue and pus that raise pressure inside the skull and cause swelling, vision loss and memory problems. According to a systematic review in the journal Medical Mycology, 60 to 70 percent of patients die even with aggressive antifungal treatment, sometimes combined with extensive surgery. Unusually, about half of infections occur in people with no known immune weakness. Researchers believe the mold enters the body when inhaled or through an open skin wound, then travels through the bloodstream to the brain. Nearly nine in ten samples in the study came from brain tissue; about 12 percent came from lung tissue, supporting inhalation as a likely route of infection. Treatment is grueling. Physicians typically combine extensive surgery to remove the abscesses with multiple antifungal medications, yet the infection often proves fatal anyway. Early symptoms can resemble other brain infections — headaches, confusion, vision changes — which means the rare mold is frequently not suspected until the illness is far advanced. ## Where the Brain Fungus Is Showing Up Cases clustered most heavily in California with six infections, followed by Florida and Texas with five each and Pennsylvania with four. But Cladophialophora bantiana — found in soil and decaying matter around the world — could be anywhere, and researchers believe current counts underestimate the true toll because testing depends on samples sent to the specialized laboratory. There is no federal tracking system for the infection, and public health officials say that must change. A fungal brain infection this lethal, they argue, deserves the same surveillance infrastructure as other emerging pathogens. Researchers stress that the 48 confirmed cases almost certainly undercount the true toll. "We think that we're probably undersampling," one investigator said — meaning the infection's actual incidence in the United States is likely higher than the laboratory data show. ## Why Scientists Cannot Explain the Brain Fungus Surge "Reasons for the apparent increase are unknown," the CDC brain fungus report's authors wrote. Possible explanations include better genetic testing, a warming climate expanding the mold's range, or environmental disruption — but none has been proven. Researchers also caution that wider use of broad genetic testing may be uncovering cases that previously went undiagnosed. For now, the CDC urges heightened awareness among clinicians: a severe fungal brain infection with no clear cause, especially in an older adult, may warrant testing for the rare mold. With no national tracking and no clear explanation for its rise, the brain fungus remains one of American public health's most unsettling mysteries.