Dangerous Fungi Are Spreading Globally, Fueled by Climate Change and Human Activity

Dangerous fungi, including the highly resistant yeast <i>Candida auris</i>, are proliferating globally, posing an escalating threat to public health. This rise is attributed to a confluence of factors, including a warming climate, increased human medical interventions, and widespread use of antifungal medications, according to infectious disease experts.

<i>Candida auris</i>, first identified in 2009, has rapidly spread across continents since 2015, sickening tens of thousands and causing tens of thousands of infections annually in the U.S. alone. With a mortality rate of up to 60%, it is now considered one of the world's highest-priority fungal threats by the World Health Organization.

"We are creating an environment that is favoring pathogenic fungi and drug resistance," said Dr. Andrej Spec, a fungal-disease specialist at Washington University School of Medicine in St. Louis. "That means they are likely becoming better at infecting us, and also at evading our treatments. That’s a bad combination."

Experts believe that rising global temperatures are driving the evolution of fungal pathogens, enabling them to thrive in environments previously too warm for survival. <i>Candida auris</i>, for instance, can now survive at temperatures up to 107°F (41.6°C), making human bodies a more hospitable environment. Changing weather patterns are also expanding the geographic range of some fungi.

Evolving Threats

The proliferation of <i>Candida auris</i> is just one example of a larger trend. Other fungi, once confined to plants or specific geographic regions, are now emerging as threats to human health. A mold that previously only infected trees has recently caused infections in people, and a brain-attacking mold variety has quadrupled in cases over the past two years.

Furthermore, the increasing use of antifungal drugs in medicine, agriculture, and livestock farming has driven the evolution of drug-resistant strains. <i>Candida auris</i> exhibits high resistance to many antifungal medications, with a growing number of infections becoming pan-resistant, meaning no available drugs are effective.

Advancements in medicine, while beneficial, also contribute to increased vulnerability. Millions of people in the U.S. take immune-suppressing drugs for autoimmune conditions and cancer, making them more susceptible to severe fungal infections. Additionally, the increased reliance on invasive medical devices like ventilators and heart-lung machines can create entry points for fungi into the body.

A Growing Concern

In the U.S., <i>Candida auris</i> cases have surged. States like Texas, New York, Nevada, Florida, and California have reported the highest numbers. What was once a rare disease primarily affecting the elderly and immunocompromised in healthcare settings is now infecting a broader range of individuals, including younger and healthier people. It is also causing new types of infections, such as vaginal yeast infections and urinary tract infections, that are proving difficult to treat.

Public health officials worry that <i>Candida auris</i> could become as widespread as MRSA (methicillin-resistant <i>Staphylococcus aureus</i>), a superbug bacteria that has transitioned from hospitals to communities.

Beyond <i>Candida auris</i>, other fungal diseases are also changing. <i>Histoplasma</i>, a fungus historically confined to certain U.S. regions, is moving northward and westward. Valley fever, caused by inhaling fungal spores, is spreading to areas previously considered too wet or cold. Even common infections like ringworm are evolving, with a new, highly contagious, and drug-resistant species spreading globally.

In South America, outbreaks of a disfiguring skin disease caused by a <i>Sporothrix</i> fungus have sickened cats, dogs, and people. This virulent strain, named <i>Sporothrix brasiliensis</i>, is primarily spread by cats and has seen a dramatic increase in cases across Brazil and neighboring countries, raising concerns about its eventual spread to the U.S.

Addressing the Challenge

Infectious disease experts and public health officials are working to address the rising threat of fungal pathogens through increased surveillance, development of new diagnostic tools, and research into novel treatments. Dr. Tom Chiller, a former chief of the fungal-diseases branch at the CDC, has been a vocal advocate for fungal disease awareness for decades. He emphasizes the importance of early diagnosis, noting that many fungal infections, like valley fever, are often misdiagnosed or diagnosed late, significantly impacting patient outcomes.

New diagnostic tests for diseases like valley fever are being developed, aiming to reduce the delay in diagnosis. However, the evolving nature of fungi and their increasing resistance to treatments present a formidable challenge. As Dr. Chiller noted, the emergence of dangerous fungi like <i>Candida auris</i> serves as a critical warning about the potential for novel and devastating diseases to arise.