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The CDC reports a significant rise in detected cases of Cladophialophora bantiana, a rare fungal infection that causes brain abscesses. Detected cases quadrupled between 2023 and 2025, with a case-fatality rate reaching 70%. Researchers warn that the infection increasingly affects individuals with healthy immune systems, though the exact cause of the rise remains unclear.
The CDC has issued a warning after researchers identified a fourfold increase in detected cases of Cladophialophora bantiana, a rare fungal infection that causes deadly brain abscesses. The findings, published in the Morbidity and Mortality Weekly Report, show that cases jumped from an annual average of fewer than five to 14 detected cases in 2025. This surge is concerning because the infection, which carries a case-fatality rate of up to 70%, is increasingly appearing in patients with apparently healthy immune systems.
A clinical reference laboratory at the University of Washington identified 48 confirmed cases and one probable case of C. bantiana infection between January 2009 and July 2026. While annual case counts remained low, ranging from one to five per year from 2009 to 2023, the numbers rose sharply to eight cases in 2024 and 14 cases in 2025. The case rate for this fungus more than tripled from an annual average of 8.4 cases per 1,000 CNS specimens in 2017-2023 to 26 cases per 1,000 specimens in 2025.
Most infections target the central nervous system (CNS), with 88% of cases detected in intracranial tissue specimens. The remaining 12% were found in lung specimens, suggesting a presumed respiratory infection route via inhalation or direct injury. The cases were geographically widespread, detected in samples from 21 states and the District of Columbia. California reported the highest number of cases with six, followed by Florida and Texas with five each, and Pennsylvania with four.
The median age of patients was 68 years. Researchers emphasized that unlike many fungal infections, C. bantiana poses a high risk of death even in individuals without profound immunosuppression. Joshua Lieberman, MD, PhD, of the University of Washington School of Medicine, noted that the true incidence is likely underestimated due to the difficulty of growing molds in laboratory settings and potential undersampling.
High Mortality in Healthy Patients
The rise in C. bantiana cases is significant because it challenges the assumption that severe fungal infections primarily affect immunocompromised patients. Lieberman stated that it is “alarming” to see these infections in otherwise healthy patients. The 70% case-fatality rate makes this one of the most dangerous fungal pathogens affecting the brain. For clinicians, the increasing prevalence means that rare causes must be considered earlier in patients presenting with brain abscesses, especially when routine cultures and cerebrospinal fluid tests fail to provide a diagnosis. The geographic spread across 21 states indicates that this is not a localized issue but a national public health concern.
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Climate Change and Diagnostic Challenges
The reasons for the surge in detected cases are not fully understood. Lieberman suggested that the increase could be partly due to more submitted specimens and improved detection methods, such as molecular testing. However, he also pointed to environmental factors, including a warming world and climate change. Evidence suggests that some fungal pathogens are adapting to higher temperatures, potentially enhancing their ability to infect humans. Additionally, human encroachment on the environmental reservoirs of C. bantiana may be increasing exposure risks. The difficulty in culturing these molds means that current data likely represents an underestimate of the true incidence.
“It’s alarming that it occurs outside of those typical high-risk populations who have pretty profound immunosuppression.”
— Joshua Lieberman, MD, PhD, University of Washington School of Medicine
Unclear Causes Behind the Surge
While the rise in detected cases is confirmed, the exact drivers of this increase remain unclear. It is not yet determined whether the surge reflects a true increase in infections or simply better detection and increased testing. The mechanism by which C. bantiana preferentially targets the brain and the specific environmental triggers causing the rise are still “a little bit of a mystery”, according to Lieberman. Furthermore, because undersampling is suspected, the true national burden of the disease is unknown.
Enhanced Surveillance and Treatment Protocols
Clinicians are advised to consider C. bantiana in cases of brain abscesses with no clear diagnosis, particularly in apparently healthy individuals. Treatment protocols involve surgical excision of abscesses combined with combination antifungal therapy using liposomal amphotericin B, posaconazole or voriconazole, and flucytosine. Future research will likely focus on improving diagnostic sensitivity to better track the incidence and on understanding the environmental factors contributing to the spread of this deadly fungus.
Key Questions
What is Cladophialophora bantiana?
Cladophialophora bantiana is a rare type of fungus that primarily causes brain abscesses. It is considered a neurotropic mold, meaning it has a tendency to infect the central nervous system. The infection is associated with a high case-fatality rate of up to 70%.
Who is at risk for this infection?
While many fungal infections affect immunocompromised patients, C. bantiana has been detected in otherwise healthy individuals with no known immune deficiencies. The median age of patients in the reported cases was 68 years, but cases have occurred across various age groups.
How is the infection diagnosed and treated?
Diagnosis often requires specialized molecular testing or biopsy of brain tissue, as routine cultures may fail. Treatment typically involves surgical removal of the abscess combined with aggressive antifungal medication, including amphotericin B and azoles.
Is this a new disease?
No, C. bantiana is not new, but it is rare. The news stems from a fourfold increase in detected cases in recent years, raising concerns about its changing epidemiology and potential links to climate change.
Source: rss
