Deadly Brain-Targeting Mold Surges Across the United States

A rare and frequently fatal mold that targets the human brain has shown a noticeable increase in detected cases over the past decade, according to a new study from researchers at the University of Washington and the Centers for Disease Control and Prevention. The findings, published in the CDC’s Morbidity and Mortality Weekly Report, highlight a fourfold surge in the frequency of positive samples tested at a specialized UW reference laboratory between recent periods, raising fresh concerns among microbiologists.

Unlike many invasive fungal infections that typically exploit pre-existing vulnerabilities, Cladophialophora bantiana behaves differently. Roughly half of all documented infections occur in individuals with fully healthy immune systems. When the mold enters the human body, it exhibits a distinct preference for attacking the brain, frequently resulting in life-threatening abscesses. Even with aggressive medical treatment, the mortality rate associated with these infections remains exceptionally high, ranging between 60 and 70 percent.

Despite being first discovered inside a brain abscess in 1911, the pathogen remains shrouded in mystery. Scientists still do not fully understand its natural environmental reservoir, how it typically infects humans, or why it selectively targets the central nervous system. While researchers suspect that people may inhale spores from the environment or contract the fungus through initial skin exposure, concrete data is lacking. Furthermore, because there is no routine national surveillance system for the mold and doctors are not legally obligated to report suspected cases, the true public health burden remains difficult to gauge.

Investigators analyzed data gathered from January 2009 through July 2026, identifying 48 confirmed cases and one probable case spanning 21 states and Washington, D.C. While annual detections hovered between one and five cases for many years, numbers began climbing notably after 2017 and escalated sharply starting in 2023. Researchers controlled for fluctuations in overall testing volumes and concluded that the upward trend represents a genuine increase in pathogen encounters rather than merely an artifact of increased clinical screening.