A rare fungus that attacks the brain is spreading in the US. The infection can kill up to 70% of patients.

A rare fungus, Cladophialophora bantiana, is reported in the United States and can cause brain abscesses with a mortality rate of 60-70% according to the CDC. The number of detected cases has increased; between 2009 and 2023, one to five cases were identified annually at a University of Washington reference laboratory, with an increase to eight in 2024 and fourteen in 2025. Researchers identified 48 confirmed and one probable case from 21 states and the District of Columbia between January 2009 and July 2026, with most cases in California, Florida, Texas, and Pennsylvania.
The infection is not limited to immunocompromised individuals, as approximately half of infected patients lacked a known condition causing immunodeficiency. The fungus is a pigmented, microscopic organism with an affinity for the central nervous system. Infection appears to occur when spores are inhaled or enter through skin wounds, potentially reaching the brain via the bloodstream, resulting in brain abscesses.
Data analysis shows a significant increase in detection rates among CNS samples; the rate increased by approximately four times between 2023 and 2025. Currently, there is no national surveillance system for this infection, and experts await more data to determine the cause of the rising incidence and the natural reservoir of the fungus.

* Cladophialophora bantiana can cause brain abscesses with a mortality rate of 60-70%.
* Data from a University of Washington reference laboratory showed between one and five cases identified per year between 2009 and 2023.
* The number of detected cases reached eight in 2024 and fourteen in 2025.
* Detection rates increased by approximately four times between 2023 and 2025.
* Between January 2009 and July 2026, researchers identified 48 confirmed and one probable case from 21 states and the District of Columbia.
* Most cases were reported in California, Florida, Texas, and Pennsylvania.
* Approximately half of infected patients did not have a previously known condition causing immunodeficiency.
* Out of 49 identified cases, 88% were detected in central nervous system tissue samples, and six cases were identified in the lungs.
* The increase rate among CNS samples from 2017-2023 averaged 8.4 cases per 1,000 samples; this rate reached 26 cases per 1,000 samples in 2025.
* The United States currently lacks a national routine surveillance system for infections with Cladophialophora bantiana.

The narrative presents a high-stakes medical mystery where a dangerous pathogen is increasing in prevalence across diverse populations, yet the underlying mechanism and incidence drivers remain unknown. The focus shifts from understanding the immediate threat—a 60-70% mortality risk—to grappling with epidemiological uncertainty. The data regarding case increases is explicitly presented as statistically significant, suggesting a genuine escalation that demands systemic investigation, particularly given the lack of a national surveillance framework for this specific fungal infection.
A critical pattern emerges around the tension between observable change and established knowledge: the increase in cases does not align solely with increased sampling, pointing toward a potential ecological or environmental shift affecting the fungus's reservoir or transmission pathway. The fact that infections occur across states with varied environmental conditions, without exclusive reliance on immune deficiency, challenges simplistic risk models. The system exhibits an 'Authority Game' by presenting alarming statistics and attributing them to an unknown trend, implicitly demanding action while simultaneously admitting the lack of a confirmed cause—a state where public health urgency clashes with scientific incompleteness.
The implications suggest that risks associated with novel or emerging zoonotic/environmental pathogens require surveillance systems robust enough to track subtle ecological changes rather than waiting for overt clinical outbreaks. The missing piece is the reservoir and environmental factors driving the incidence increase, which represents a gap in understanding that directly impacts future prevention strategies. What processes are being overlooked when the observed epidemiological rise seems decoupled from immediate intervention or known vulnerability profiles?