Deadly fungal brain infection is on the rise as experts hunt for answers

A rare but deadly mould infection that attacks human brains is on the rise. Scientists say there has been a noticeable increase in the number of cases involving the fungus Cladophialophora bantiana in the past decade. Scientists at the University of Washington and the Centers for Disease Control and Prevention studied reports of the confirmed cases and found the spike has been particularly high since 2023. It remains unclear how it infects a person, making it difficult to ascertain why it is on the rise.

"Reasons for the apparent increase are unknown," authors wrote in the paper published last week in the CDC’s Morbidity and Mortality Weekly Report.

Fungal infections are rare in humans, with those attacking the brain even rarer. Even when they reach the brain, they are an offshoot of another disease somewhere else in the body. People with a compromised immune system are more prone to falling prey to such infections.

C. bantiana remains a mystery

However, C. bantiana breaks these rules. Its main target is the brain, where it forms pockets of pus filled with the fungus. Study author Joshua Lieberman says the mortality rate is between 60 and 70 per cent, and it can attack anyone. The study states that nearly half the patients suffering from this fungus are those with healthy immune systems.

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The researchers analysed data from a specialised clinical reference laboratory at the University of Washington, which has had confirmed cases of the C. bantiana fungal infection for several years. The team compared the frequency of positive samples with the total number of samples sent in for all suspected fungal brain infections. This revealed the frequency of these cases.

Between January 2009 and July 2026, 48 confirmed cases of the fungal infection and one probable case of C. bantiana were found in 21 states and Washington, DC. Between 2009 and 2023, one to five cases were detected each year. But this number increased sharply in 2024, when eight cases were detected, with 14 confirmed cases in 2025.

The study states that the rise seems to have started in 2017 but started becoming clear in 2021. From an average of 8.4 cases of C. bantiana for every 1,000 samples between 2017 and 2023, the number saw a fourfold increase between 2023 and 2025.

The fungus was first found inside a brain abscess in 1911, but little is known about it even today. Scientists don't even know where it naturally resides. The infection route has never been confirmed, but it is believed to enter through the skin or by inhalation before travelling to the brain. Why even healthy people fall prey to it also remains unknown. However, experts are most concerned about the rise in numbers and stress on systematic data collection for a clear picture of the caseload.