A Brain-Attacking Fungus With a 70% Kill Rate Is Surging Across the US

A Rare and Deadly Mold on the Move

A rare fungal infection that can strike healthy people is rising across the U.S., prompting calls from public health officials for heightened awareness and national tracking. The culprit is Cladophialophora bantiana, a black yeast-like mold that can infect the brain and contains a dark pigment called melanin, according to a new report from the Centers for Disease Control and Prevention. What makes this story especially alarming isn't just the infection's lethality — it's how fast it appears to be spreading, and how little scientists understand about why.

From 2009 through 2023, the United States recorded one to five cases a year. That total rose to eight in 2024 and reached 14 in 2025. To make sure the increase wasn't simply due to more testing, researchers compared the number of infections with the total number of brain tissue samples tested for fungi. They found that detections rose from 8.4 cases per 1,000 specimens during 2017–2023 to 26 cases per 1,000 specimens in 2025. That's a striking jump — one that researchers say cannot be explained away by better diagnostics alone.

What This Fungus Does to the Brain

The pathogen primarily invades brain tissue, forming severe, pus-filled abscesses that cause devastating neurological damage. Despite aggressive treatment, 60 to 70 percent of patients in earlier case series died. The best chance of survival comes from a combination of surgical removal of the abscesses and several antifungal drugs over a long period. Even with that treatment approach, the odds remain grim for many patients.

Between January 2009 and July 2026, researchers identified 48 confirmed cases and one probable case of C. bantiana in tissue samples from 21 states and the District of Columbia. The median patient age was 68 years old. Samples came from 21 states and Washington, D.C., led by California, Florida, Texas, and Pennsylvania. The geographic spread alone signals that this is not a localized problem.

Healthy People Are Not Immune

Unlike many fungal infections that mainly affect people with weakened immune systems, about half of C. bantiana infections occur in otherwise healthy people. Researchers believe the mold enters the body when it is inhaled or through a skin wound, then travels through the bloodstream to the brain. That means even a minor cut while gardening or working outdoors could theoretically serve as an entry point.

Scientists remain baffled by the underlying cause of the surge, as there is currently no centralized federal tracking system specifically dedicated to monitoring the fungus. "Reasons for the apparent increase are unknown," the CDC report stated, calling for systematic national reporting mechanisms to better track the pathogen. As changing environmental conditions potentially play a role in spore proliferation, medical professionals are urging hospitals nationwide to stay vigilant for unusual neurological symptoms.

A Call for Vigilance — and Better Tracking

The CDC report emphasizes that clinicians should consider C. bantiana when evaluating patients with signs and symptoms of a brain abscess. Identifying the organism can be challenging, making laboratory testing and clinical assessment important. Delayed or missed diagnosis is a serious concern, particularly given how quickly the infection can become fatal.

Despite its severity, C. bantiana remains rare. The reported increase in laboratory detections does not establish that the United States is experiencing a nationwide outbreak. Still, the trajectory is hard to ignore. With no national surveillance system in place and no clear explanation for the surge, public health researchers are pressing for broader data collection across clinical laboratories nationwide. Understanding the scale of this threat is the first step toward containing it — and right now, that picture remains dangerously incomplete.