Deadly Brain-Liquifying Fungus Cases Surge in US, Scientists Baffled
The CDC is issuing warnings about a rare fungus that kills up to 70% of those infected, with cases quadrupling in two years.
Cases of a rare and deadly fungus that liquefies the brain have quadrupled in the United States over the past two years, prompting concern from the Centers for Disease Control and Prevention (CDC). The fungus, known as Cladophialophora Bantiana (C. Bantiana), is a black mold found in soil and decaying matter worldwide. It is estimated to kill up to 70% of the individuals it infects.
Rising Incidence
The CDC reports that between January 2009 and July 2026, researchers identified 48 confirmed cases and one probable case of C. Bantiana infections in the U.S. While the number of cases remained low, ranging from one to five per year between 2009 and 2023, there was a notable increase to eight cases in 2024, followed by a jump to 14 cases in 2025. This represents a four-fold increase in reported cases within two years.
Researchers at the University of Washington observed a similar trend. From 2017 to 2023, an average of 8.4 cases per 1,000 central nervous system (CNS) specimens submitted for fungal analysis were detected. By 2025, this number had increased by 210% to 26 cases per 1,000 specimens. Lead author Joshua Lieberman noted that the actual incidence may be even higher, stating, "We think that we’re probably undersampling. We think that that’s probably going to be an underestimate of the true incidence."
Most documented cases, 88%, were detected from brain samples, with the remaining 12% from lung samples. The infection has been reported in 21 U.S. states and the District of Columbia, with California (six cases), Florida (five), and Texas (five) having the highest numbers. Pennsylvania reported four cases.
Unknown Spread and Risk Factors
Scientists remain uncertain about how the fungus spreads to humans. The CDC presumes infection occurs through inhalation of the spores or when the fungus enters an open wound. Once inside the body, the fungus typically targets the brain, causing abscesses, swelling, and severe neurological issues such as vision and memory loss.
While immunocompromised individuals are typically at higher risk for fungal infections, C. Bantiana does not exclusively target this group. Data indicates that approximately half of those infected had seemingly healthy immune systems, a finding Lieberman described as "alarming."
Treatment Challenges and Potential Causes
Treating C. Bantiana infections is difficult. By the time symptoms are recognized, the condition can be misdiagnosed as a brain tumor. Even with aggressive treatment, including surgery and antifungal medication, survival rates are low. One case described in a study involved a 44-year-old who received optimal treatment but died within three months of infection.
While the CDC has stated that the reasons for the apparent increase are unknown, Lieberman suggests that a warming climate could be a contributing factor. Researchers have warned that rising global temperatures may allow more fungal pathogens to thrive and adapt to new environments. Additionally, an increase in natural disasters could lead to more fungal outbreaks.
Historically, C. Bantiana was considered a tropical infection associated with warm climates and high humidity. However, it is now recognized as being found worldwide. A study in France documented a similar increase in C. Bantiana cases in 2022, the warmest year on record for the country since 1900.