A rare brain-infecting fungus, Cladophialophora bantiana, is on the rise in the U.S., with a significant increase in cases prompting public health officials to call for heightened awareness and tracking.
Cladophialophora bantiana, a neurotropic black mold, has seen a nearly fourfold increase in detections across the United States between 2023 and 2025. This rare fungal infection poses a serious threat, particularly as it can affect healthy individuals, leading to calls from public health officials for increased awareness and national tracking.
According to a recent report from the Centers for Disease Control and Prevention (CDC), C. bantiana is a black yeast-like mold that can infect the brain and contains a dark pigment known as melanin. Data from a microbiology laboratory at the University of Washington indicates that the detection of this dangerous fungus has surged significantly during the past few years.
Between January 2009 and July 2026, researchers identified 48 confirmed cases and one probable case of C. bantiana in tissue samples collected from 21 states and the District of Columbia. The median age of the patients affected was 68 years.
Unlike many fungal infections that primarily impact individuals with weakened immune systems, approximately half of the cases of C. bantiana occur in otherwise healthy people. Researchers believe that the mold typically enters the body through inhalation or via skin wounds, subsequently traveling through the bloodstream to the brain.
The CDC report highlights that 88% of the cases were detected in brain tissue samples, while 12% were found in lung tissue. This supports the theory that respiratory inhalation is one of the primary transmission routes for this pathogen.
The infection caused by C. bantiana is severe and is associated with a fatality rate of 60% to 70%, even with aggressive medical intervention, according to a systematic review published in the journal Medical Mycology. Historically, the pathogen has been rare, with the University of Washington laboratory identifying only one to five cases annually between 2009 and 2023. However, the CDC reports a notable increase in annual cases, with eight cases recorded in 2024 and 14 in 2025.
To ensure that this increase was not merely a result of enhanced testing, researchers compared the number of infections to the total number of brain tissue samples tested for fungi. They found that detections rose from 8.4 cases per 1,000 specimens during the period from 2017 to 2023 to 26 cases per 1,000 specimens in 2025.
The reasons behind the apparent increase in cases remain unclear, prompting the CDC to call for systematic national reporting mechanisms to better track this pathogen.
Cases of C. bantiana have been reported across a wide geographic range, with the highest counts originating from California (six cases), Florida (five), Texas (five), and Pennsylvania (four). The fungus typically manifests as a brain abscess without clear external signs of infection, making early diagnosis particularly challenging.
In one documented fatal case at the University of Washington Medical Center, spinal fluid PCR tests returned negative results both one month prior to and at the time of a brain biopsy, underscoring the difficulties in detecting the mold.
Public health experts advise clinicians to consider C. bantiana when evaluating patients who exhibit signs of a brain abscess. Treatment generally involves surgical removal of the infected tissue, in conjunction with multiple antifungal medications.
As the incidence of this dangerous fungus rises, increased awareness and prompt diagnosis will be critical in managing and mitigating its impact on public health, according to the CDC.
For further details, refer to the CDC report.