The CDC is calling for more systematic surveillance of Cladophialophora bantiana, a rare fungus associated with a 60% to 70% case-fatality rate and known to cause potentially fatal brain abscesses.
The US Centers for Disease Control and Prevention (CDC) is urging greater surveillance of Cladophialophora bantiana after a clinical reference laboratory reported a substantial increase in detections of the rare and highly virulent fungus.
The findings were published Oct. 2, 2026, in the CDC's Morbidity and Mortality Weekly Report (MMWR). The report found that the frequency of C. bantiana detections at a University of Washington clinical reference laboratory increased approximately fourfold per 1,000 submitted central nervous system (CNS) specimens between 2023 and 2025.
Cases increased sharply in 2024 and 2025
From 2009 through 2023, the laboratory detected between one and five cases of C. bantiana each year. The number increased to eight cases in 2024 and 14 cases in 2025.
Between January 2009 and July 2026, 49 confirmed or probable cases were identified. Of those, 43, or 88%, were detected in intracranial CNS tissue specimens, while six, or 12%, were detected in lung specimens.
The cases originated in 21 US states and the District of Columbia.
The CDC said the increase could not be explained solely by a rise in laboratory referral volume. From 2017 through 2023, an average of 8.4 C. bantiana cases were detected per 1,000 CNS specimens submitted for broad-range fungal PCR testing at the University of Washington. By 2025, that figure had increased to 26 per 1,000.
Fungus primarily causes brain abscesses
C. bantiana is a highly virulent, neurotropic mold that predominantly causes brain abscesses in both immunocompetent and immunocompromised people.
The infection is associated with a 60% to 70% case-fatality rate, even with aggressive treatment. The CDC also noted that approximately half of patients with C. bantiana infections have no known underlying immunocompromising condition.
The environmental reservoir and precise route of infection remain poorly understood. The presumed route is inhalation or direct inoculation following a skin injury, followed by hematogenous spread to the brain. Pulmonary and cutaneous infections have also been reported, although most cases present as brain abscesses without clear evidence of infection elsewhere.
Reason for increase remains unclear
The reason for the recent increase in detections remains unknown, according to the CDC.
Researchers said additional studies are needed to better understand epidemiologic risk factors and whether changes in virulence could be contributing to the increase. The absence of routine national surveillance for C. bantiana also limits the ability to assess its epidemiology and determine whether the recent rise reflects a broader trend.
The CDC called for more systematic reporting of cases and encouraged clinical laboratories to report the number of infections they identify.
Clinicians urged to consider C. bantiana
The CDC said clinicians should consider C. bantiana when evaluating patients with signs and symptoms of a brain abscess.
Patients with confirmed infection require prompt antifungal therapy, while surgical excision of the abscess may improve outcomes in some cases, according to the report.
The findings add to growing public health attention around serious fungal threats. Although C. bantiana remains rare, the CDC said the recent increase highlights the need for improved surveillance and further research into risk factors, transmission patterns and the epidemiology of the infection.
