Infections with little-understood deadly fungus jumped 4-fold in US from 2023 to 2025
Mary Van Beusekom, MSToday at 2:36 p.m.
Fungal Infection
US detections of Cladophialophora bantiana, a rare but dangerous fungus that most often targets the central nervous system (CNS), rose fourfold from 2023 to 2025, write researchers from the University of Washington (UW) in Seattle and the Centers for Disease Control and Prevention.
For the study, published last week in Morbidity and Mortality Weekly Report, the team analyzed all C bantiana cases identified through fungal polymerase chain reaction (PCR) testing at UW’s lab from January 2009 to July 2026.
C bantiana is a highly virulent mold that carries a 60% to 70% case-fatality rate, even with aggressive treatment. Half of infected patients don’t have weakened immune systems. Experts think the route of infection is inhalation or infection of a skin lesion, followed by spread to the brain, where it causes an abscess. But little is known about the risk factors or epidemiology of the fungus.
“Furthermore, C. bantiana has only rarely been isolated from environmental sources, and many patients do not have similar exposure histories or risk factors,” the authors wrote. “National surveillance does not exist, and neither the environmental reservoir nor the route of infection is fully understood.”
Detection in lung samples backs inhalation as infection route
From 2009 to 2026, fungal PCR identified 48 confirmed infections and one probable case of C bantiana. The median patient age was 68 years. Of the 49 cases, 88% were found in brain tissue, and 12% were detected in the lung. No CNS infections were found outside of the brain.“Detection of 12% of cases in pulmonary samples supports the presumed respiratory route of infection,” the researchers wrote.
One to five cases were identified each year from 2009 to 2023, rising to eight in 2024 and 14 in 2025. From 2017 to 2023, on average, 8.4 C bantiana cases were detected per 1,000 CNS samples. But by 2025, infections spiked to 26 per 1,000, a 210% increase the authors said was not attributable to an increase in lab referral volume alone.
Cases were reported by 21 states and Washington, DC, with most originating in California (six), Florida (five), Texas (five), and Pennsylvania (four). PCR testing of cerebrospinal fluid performed before the death of the sole fatal case was negative for C bantiana in samples collected concurrently and one month before biopsy.
The authors urged clinicians to be aware of the rising incidence of C bantiana in patients with signs and symptoms of a brain abscess. “Testing can be ordered through clinical reference laboratories that offer molecular testing for fungi in tissue or CSF specimens,” they wrote.
“When possible, surgical excision should be considered, concurrently with administration of combination antifungal therapy,” they added. “Although the most effective antifungal regimen is not known, triple therapy (treatment with [the antifungal drugs] lipsosomal amphotericin B, posaconazole or voriconazole, and flucytosine) for at least 2 weeks has demonstrated some effectiveness.”