Between January 2009 and July 2026, a clinical reference laboratory at the University of Washington found one probable and 48 confirmed cases of Cladophialophora bantiana infection, noting that the number of detections grew roughly fourfold between 2023 and 2025.
Most C. bantiana infections target the central nervous system and present as brain abscesses with a case-fatality rate of up to 70%. Researchers found that 88% of the detected cases appeared in intracranial central nervous system tissue specimens, while 12% turned up in lung specimens, pointing to a presumed respiratory infection route.
Climbing Case Rates Across Twenty-One States
From an annual mean of 8.4 cases per 1,000 CNS specimens during 2017–2023, the C. bantiana case rate increased more than threefold to 26 cases per 1,000 specimens in 2025. Joshua Lieberman, MD, PhD, of the University of Washington School of Medicine in Seattle, and his colleagues detailed these findings in the Morbidity and Mortality Weekly Report.
Samples from 21 states and the District of Columbia yielded confirmed and probable cases, showing an even distribution across the United States. California recorded the highest number with six cases, followed by Florida with five, Texas with five, and Pennsylvania with four. Patients in the data set had a median age of 68 years.
Unanswered Questions Regarding Fungal Pathogens
Where people contract the fungus and why it primarily migrates to the brain remains a mystery, Lieberman noted to MedPage Today. The infection stands out because individuals with apparently healthy immune systems contract it and face a high risk of death, unlike typical high-risk populations that have profound immunosuppression.
While the rise in detected cases could stem from more submitted specimens and improved molecular testing, Lieberman pointed to a warming world and climate change as other probable drivers. A warming environment puts people at greater risk as fungal pathogens adapt to higher temperatures, alongside human encroachment on the environmental reservoir of C. bantiana.
Doctors Urge Considering Rare Causes for Unexplained Brain Abscesses
At least one other U.S. specialized fungal lab has observed a rise in detected C. bantiana cases. Because molds are difficult to grow in labs, researchers suspect that current figures underestimate the true incidence through undersampling.
For clinicians managing a brain abscess without a clear diagnosis from cerebrospinal fluid or routine culture in otherwise healthy patients, Lieberman suggested considering rare causes like C. bantiana. Treatment protocols require surgical excision of the abscesses paired with combination antifungal therapy utilizing liposomal amphotericin B, posaconazole or voriconazole, and flucytosine.
Answers to Common Questions About Cladophialophora Bantiana
What percentage of Cladophialophora bantiana infections prove fatal?
The fungal infection is linked to case-fatality rates of up to 70%.
Which U.S. state recorded the highest number of cases in the laboratory data?
California recorded the largest number of cases in the reference laboratory data, with six confirmed and probable infections.
What are the primary anatomical sites where the fungus is detected?
Among the identified cases, 88% were detected in intracranial central nervous system tissue specimens, while 12% were found in lung specimens.
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