A rare and deadly brain fungus is being detected at a rapidly increasing rate across the United States, according to new data from the Centers for Disease Control and Prevention (CDC). The organism, Cladophialophora bantiana, is a black yeast-like mould that targets the nervous system and causes infections with a fatality rate of up to 70 per cent. Data from a specialist microbiology laboratory at the University of Washington shows detections nearly quadrupled between 2023 and 2025, a surge that has prompted public health experts to call for heightened awareness and national tracking of the infection.
What Is Cladophialophora Bantiana, the Deadly Brain Fungus?
Cladophialophora bantiana is a darkly pigmented mould found in soil and decaying organic matter around the world. It contains a dark pigment called melanin, which researchers believe may help it survive and spread within the human body. Scientists say relatively little is known about how the organism infects people, though it is presumed to enter through inhalation or through a break in the skin, before travelling through the bloodstream to the brain. Unlike many invasive fungal infections that mainly threaten people with severely weakened immune systems, about half of reported C. bantiana infections occur in otherwise healthy individuals, making this particular brain fungus especially concerning for clinicians.
Once it reaches the brain, the organism can cause a devastating infection known as phaeohyphomycosis. It forms abscesses filled with pus and necrotic tissue, triggering inflammation, swelling and dangerously raised pressure inside the skull. Patients may suffer severe headaches, nausea and vomiting, along with neurological problems such as vision and memory loss. Treatment is exceptionally difficult and can require extensive surgery combined with multiple antifungal medicines. Even with aggressive medical intervention, a systematic review published in the journal Medical Mycology found the infection carries a 60 to 70 per cent fatality rate.
Why Brain Fungus Detections Are Rising
The new CDC analysis, published online on 2 October 2026 in the Morbidity and Mortality Weekly Report, tracked laboratory samples that tested positive for the organism. Between 2009 and 2023, detections stayed low and steady, averaging just one to five cases a year. Then the numbers climbed: eight cases were recorded in 2024, followed by 14 in 2025. Between January 2009 and July 2026, researchers identified 48 confirmed cases and one probable case in tissue samples sent in from 21 states and the District of Columbia. In a related measure, brain fungus detections per 1,000 central nervous system specimens submitted for analysis rose 210 per cent by 2025.
Cases have clustered most heavily in California, which reported six infections, followed by Florida and Texas with five each and Pennsylvania with four. The median patient age was 68. The CDC report notes that 88 per cent of cases were detected in brain tissue samples and 12 per cent in lung tissue, supporting the theory that breathing in the organism is one of the main routes of infection. Crucially, scientists still do not know why the numbers are climbing, where people are encountering the mould, or whether its behaviour is changing.
Brain Fungus Symptoms and Survival Odds
Early recognition remains the biggest challenge. The symptoms of a brain fungus infection are non-specific and can easily be mistaken for other neurological conditions, which delays diagnosis until the disease is advanced. Because the infection is so rare, many doctors may never encounter a case in their careers. Experts say patients with unexplained brain abscesses, persistent headaches or neurological decline that does not respond to standard treatment should be evaluated with this brain fungus in mind. Survival depends heavily on early diagnosis, surgical removal of infected tissue where possible, and prolonged courses of antifungal therapy.
No National Tracking, and Many Unanswered Questions
Perhaps most alarmingly, there is no federal system for tracking this brain fungus in the United States, meaning the true burden of disease is unknown. The CDC relied on samples sent voluntarily to a single reference laboratory, and researchers believe the figures are an underestimate. Public health officials are now urging clinicians to consider the infection in unexplained cases and are calling for a national surveillance system so the rise can be properly understood. Similar cases of this brain fungus have also been reported in Canada, the United Kingdom, Japan, India, France, Belgium, South Africa, Mexico, Brazil and Malaysia, a reminder that this is a global, not just an American, concern.
Web story: Deadly Brain Fungus Cases Nearly Quadruple in the US