UW Laboratory Reports Surge in Cladophialophora Bantiana Brain Infections

Detected cases of a rare but deadly fungal infection increased about fourfold from 2023 to 2025 at a clinical reference laboratory at the University of Washington, researchers reported. Between January 2009 and July 2026, the laboratory identified 48 confirmed cases and one probable case of the infection, which primarily targets the central nervous system and forms brain abscesses carrying a case-fatality rate of up to 70%.

Surge in Laboratory Detections Across U.S. States

Annual case counts at the testing facility ranged between one and five cases each year from 2009 through 2023. Those numbers rose to eight cases in 2024 and jumped to 14 cases in 2025. The case rate more than tripled from an annual average of 8.4 cases detected per 1,000 central nervous system specimens between 2017 and 2023, reaching 26 cases per 1,000 specimens in 2025. Among the 49 total confirmed and probable patients, the median age was 68 years, according to data published in the Morbidity and Mortality Weekly Report by Joshua Lieberman, MD, PhD, of the University of Washington School of Medicine in Seattle, and colleagues.

The infections were distributed across 21 states and the District of Columbia. California recorded the highest total with six cases, followed by Florida with five, Texas with five, and Pennsylvania with four. Of all specimens analyzed, 88% came from intracranial central nervous system tissue, while 12% were detected in lung specimens. Lieberman stated that this distribution points to a presumed respiratory infection route or direct inoculation through a skin injury.

C. Bantiana Infects Healthy People Through Unknown Routes

While molds are notoriously difficult to grow in standard laboratory environments, researchers believe current figures likely underestimate the true incidence because of undersampling. Lieberman noted that distinguishing features of these infections include their capacity to strike apparently healthy individuals who lack profound immunosuppression, putting them at severe risk of death. Where patients contract the fungus and why it localizes in the brain remain unclear.

C. bantiana is a rare but important cause of brain abscess in both healthy and immunosuppressed people.

Joshua Lieberman

Researchers are examining several hypotheses for the recent increase, including improved molecular testing methods and a higher volume of submitted specimens. Lieberman also pointed to a warming global climate as a potential driver, explaining that rising environmental temperatures may increase fungal infection risks as pathogens adapt to tolerate heat. Human encroachment on natural environmental reservoirs of the fungus could also elevate exposure levels.

Clinicians Must Use Surgery and Aggressive Antifungal Regimens

Clinicians treating patients with brain abscesses who do not yield a diagnosis through cerebrospinal fluid analysis or routine cultures—especially individuals with healthy immune systems—should consider rare pathogens such as C. bantiana. Treatment protocols require surgical removal of the abscesses combined with aggressive antifungal regimens. Medical management typically involves liposomal amphotericin B, flucytosine, and either posaconazole or voriconazole.