Surge in Rare Fungal Infection Raises Concerns

A rare fungal infection, which poses a risk even to healthy individuals, is becoming more prevalent in the U.S. Public health officials are increasingly urging for greater awareness and the establishment of national tracking.

The culprit here is Cladophialophora bantiana (C. bantiana), a black yeast-like mold known for its ability to infect the brain. It contains a pigment called melanin, as noted by a recent report from the Centers for Disease Control and Prevention (CDC).

Data from a microbiology lab at the University of Washington indicates that the instances of this fungus have nearly quadrupled from 2023 to 2025.

Between January 2009 and July 2026, researchers documented 48 confirmed cases and one probable case of C. bantiana found in tissue samples across 21 states and the District of Columbia, with a median patient age of 68 years.

What’s noteworthy about C. bantiana is that, unlike many similar fungal infections which usually target those with weakened immune systems, about half of its cases are found in otherwise healthy people.

Experts suggest that the mold typically enters the body through inhalation or through wounds on the skin, eventually making its way to the brain via the bloodstream.

According to the CDC report, 88% of the cases were found in brain tissue samples, while 12% were in lung tissue, lending credence to the idea that respiratory inhalation is a primary mode of transmission.

The fungus leads to severe infections with a staggering fatality rate of 60% to 70%, even with intensive medical treatment, as highlighted in a systematic review featured in Medical Mycology.

Historically, this pathogen has been rare, with cases typically ranging from one to five annually between 2009 and 2023. However, the CDC has pointed out a sharp increase in annual cases—going from eight in 2024 to 14 in 2025.

To rule out the possibility that this spike in cases was merely a result of increased testing, researchers analyzed the rate of infections relative to the overall number of brain tissue samples examined for fungi. They found that detectable cases surged from 8.4 for every 1,000 specimens between 2017 and 2023 to 26 for every 1,000 in 2025.

“The reasons behind the noticeable uptick remain unclear,” the CDC report mentioned, emphasizing the necessity for systematic national reporting to effectively monitor the pathogen’s spread.

The cases have been reported from a diverse array of locations, with California leading with six cases, followed by Florida and Texas with five each, and Pennsylvania with four.

Public health officials are calling on healthcare providers to keep fungal pathogens in mind when diagnosing brain abscesses, stressing the need for national tracking to address this growing concern.

Because C. bantiana usually appears as a brain abscess without obvious signs of infection, early detection can be quite tricky. In one documented case at the University of Washington Medical Center, tests on spinal fluid produced negative results both prior to and during a brain biopsy, underscoring the challenges in identifying this mold.

Health professionals are advised to think about C. bantiana for patients showing symptoms consistent with a brain abscess. Typically, treatment necessitates surgery to remove infected tissue, supplemented with various antifungal medications.