Mystery Surge: Deadly Brain Fungus

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A fungus that eats into the brain and kills up to seven in ten people it infects is showing up far more often across the United States, federal health officials say.

Quick Take

The Centers for Disease Control and Prevention (CDC) reports detections of Cladophialophora bantiana jumped fourfold between 2023 and 2025.
A single reference lab found 48 confirmed cases and one probable case from January 2009 through July 2026, mostly in brain tissue.
Infection carries a 60 to 70 percent death rate, and no national tracking system exists for this fungus.
Cases clustered heaviest in California, Florida, Texas, and Pennsylvania, though scientists still don’t know why numbers are climbing.

What The New CDC Report Found

The CDC published its findings in the Morbidity and Mortality Weekly Report on October 2, 2026. Researchers tracked lab samples testing positive for Cladophialophora bantiana, a mold that targets the nervous system. Detections stayed low and steady for years, averaging one to five cases annually between 2009 and 2023. Then the numbers spiked. Cases hit eight in 2024 and 14 in 2025, a fourfold jump in just two years.

The data came from one specialized laboratory at the University of Washington in Seattle, which works with the CDC to identify rare fungal infections using broad genetic testing. Over the full study period, the lab confirmed 48 cases plus one probable case, pulled from clinical samples sent in from 22 jurisdictions across the country. Nearly 9 in 10 of those samples came from brain and spinal tissue.

Where Cases Are Concentrated And Who’s At Risk

Patients turned up in 21 states and the District of Columbia, with no single region spared. The heaviest concentrations landed in California, Florida, Texas, and Pennsylvania. That spread suggests the fungus isn’t tied to one climate or one corner of the country. Researchers also found the mold in lung samples, which backs up the theory that people breathe in fungal spores before the infection travels to the brain.

Cladophialophora bantiana lives in soil and rotting plant matter worldwide, and most people who encounter it never get sick. Infection usually strikes through a cut, a wound, or inhaled spores that slip past the body’s defenses. Once it reaches brain tissue, it forms abscesses that are brutally hard to treat. Doctors often need a combination of antifungal drugs and surgery just to give a patient a fighting chance.

Why This Fungus Is So Dangerous

The case-fatality rate for Cladophialophora bantiana runs between 60 and 70 percent, according to the CDC’s own summary of the report. That puts it among the deadliest fungal threats doctors encounter, rare or not. Symptoms can mimic a stroke, a tumor, or meningitis, which means diagnosis often comes late. By the time doctors identify the fungus correctly, the infection may already have caused serious brain damage.

Less than 200 cases of this type of brain infection have ever been reported worldwide, spread across 26 countries, with India and the United States accounting for the largest shares. That global rarity is exactly why a sudden uptick in American detections grabbed the CDC’s attention. Doctors who have never seen a case in their careers could suddenly be the ones diagnosing it.

The Surveillance Gap Behind The Numbers

Here’s the catch worth understanding: no national surveillance system exists for this fungus. Unlike diseases such as measles or tuberculosis, doctors aren’t required to report Cladophialophora bantiana cases to health departments. That means the real count could run higher or lower than what one lab captured, since fungal diseases are notoriously underdiagnosed and underreported nationwide.

🚨 BREAKING: Cases of a rare brain-infecting fungus are reportedly rising in the U.S. Cladophialophora bantiana can cause deadly brain infections, with a reported mortality rate of up to 70%.

— SARS‑CoV‑2 (COVID-19) (@COVID19_disease) October 15, 2026

Scientists still don’t know exactly why cases rose so sharply starting in 2023, and CDC researchers say more study is needed before drawing firm conclusions about the cause. What’s clear is that the detection trend is real, based on consistent testing at the same laboratory over nearly two decades. For now, health officials are urging doctors to keep this fungus on their radar, especially when common treatments for brain infections fail to work.