Deadly Brain-Liquefying Fungus Cases Surge Fourfold in U.S.

Health experts are sounding the alarm over a concerning rise in cases of a rare but deadly fungus that can liquefy parts of the brain, killing an estimated 60 to 70 percent of those infected. Researchers from the University of Washington and the Centers for Disease Control and Prevention (CDC) observed a fourfold increase in infections of Cladophialophora bantiana (C. bantiana) over a two-year period.

Between 2009 and 2023, the University of Washington's reference lab detected between one and five cases of the fungus annually. However, this number jumped to eight cases in 2024 and 14 cases in 2025. In total, 48 confirmed cases of C. bantiana were identified in the U.S. between January 2009 and July 2026, with scientists suspecting that the actual number may be higher.

The reasons for this apparent increase are currently unknown, though researchers suggest climate change could be a contributing factor. Cases have been reported in 21 states and Washington D.C., with California identifying the highest number at six cases during the study period. Florida and Texas each reported five cases, and Pennsylvania identified four.

Dr. Joshua Lieberman, lead author of the study from the University of Washington School of Medicine, expressed concern that the fungus is now affecting individuals outside of typical high-risk groups, such as those with severely compromised immune systems. "People who have apparently healthy immune systems get the infection and are also at high risk of death," Lieberman stated.

While little is known about how C. bantiana infects humans, it is presumed to enter the body through inhalation from soil, particularly in humid or subtropical regions. The fungus's ability to produce melanin, a pigment that protects it, is believed to help it cross the blood-brain barrier. Once in the brain, it causes phaeohyphomycosis, a severe disease characterized by abscesses filled with pus and dead tissue, leading to inflammation and increased pressure within the skull.

These abscesses can present symptoms such as severe headaches, nausea, and vomiting, and on brain scans, they can be mistaken for tumors or strokes, potentially causing diagnostic delays. The study noted that from 2017 to 2023, an average of 8.4 cases per 1,000 central nervous system samples were detected. This number surged to 26 cases per 1,000 samples by 2025, marking a 210% increase.

Of the identified cases, 88 percent were found in brain tissue and 12 percent in lung tissue. The average age of infected patients was 68. The report highlighted that only about half of those infected had weakened immune systems, contrary to the usual pattern for mold infections.

Even with aggressive treatment, including surgery to remove lesions and drain abscesses, the mortality rate remains high, between 60 and 70 percent. The study authors urged healthcare providers to be aware of the increasing number of cases and the associated signs and symptoms of brain abscesses. C. bantiana infections have also been identified internationally, with cases reported in Canada, the UK, Japan, India, France, Belgium, South Africa, Mexico, Brazil, and Malaysia.