A rare and potentially deadly fungus that can affect the brain is being reported with increasing frequency in the United States, raising concern among scientists.
According to an international media report, the fungus can cause brain abscesses and, in severe cases, may prove fatal.
US Centers for Disease Control and Prevention (CDC) data cited in the report shows that cases of Cladophialophora bantiana rose from eight in 2024 to 14 in 2025.
Between January 2009 and July 2026, a total of 48 confirmed cases and one probable case of the infection were identified in the United States, according to the report.
The fungus is generally described as a type of black mold that can be found in soil and decaying organic matter.
Once infection occurs, it can affect the brain and cause abscesses, potentially leading to swelling and neurological problems. Reported symptoms may include memory impairment and vision problems.
Experts say diagnosing the infection can be difficult because its symptoms may resemble those of other conditions, including brain tumors. The report states that the fatality rate can reach as high as 70% in some circumstances.
The report also noted an increase in the fungus detected at a laboratory at Washington University.
Between 2017 and 2023, an average of 8.4 cases were identified per 1,000 brain and central nervous system samples. In 2025, the figure increased to 26 cases per 1,000 samples — an increase of approximately 210%.
Experts believe the available figures may not fully reflect the actual situation because some infections could go undiagnosed.
Cases have been reported across 21 US states and Washington, DC.
How Does the Fungus Spread?
Scientists have not yet determined exactly how the fungus reaches humans. One possibility is that fungal spores enter the body through inhalation or cause infection through an open wound.
Importantly, some reported patients had normal immune systems, suggesting that the risk may not be limited to people with weakened immunity.
Experts say further research and improved surveillance are needed to better understand the reasons behind the rise in cases, how the infection spreads and how it can be treated effectively.