Review of 180 studies examines climate links to Candida auris threats

A review of about 180 studies concludes that the rapid emergence of the multidrug-resistant yeast Candida auris, also known as Candidozyma auris, may provide clues about how other fungi could become serious human pathogens. Researchers Carla Schuh and Chaitanya Gokhale of the University of Würzburg’s Biocentre found numerous indications that climate change could have contributed to the fungus’s ability to infect humans, although their literature analysis does not establish climate change as the cause. The review instead presents climate change as a hypothesis supported by the organism’s unusual heat tolerance, rapid international spread and the overlapping appearance of distinct genetic lineages on several continents.

Only a few hundred of the estimated three to five million fungal species on Earth are capable of infecting humans, partly because most cannot grow at the human body temperature of 37 degrees Celsius. The researchers argue that rising temperatures associated with climate change could allow additional fungi to adapt to warmer conditions and potentially colonize the human body. That pathway remains unproven for C. auris.

Its original habitat is still unknown, and possible locations include coastal areas, wetlands and other saline environments. Agricultural fungicide use and other human-driven environmental changes are also under discussion, leaving several possible explanations for the organism’s sudden appearance and rapid spread. C. auris was first identified in Japan in 2009 in a patient’s ear, a discovery that inspired its common name, “yeast of the ear.” Within a few years, genetically distinct lineages had been detected on several continents.

The Würzburg researchers describe this pattern as an indication of a globally active selective factor, but they also caution that it does not by itself prove the role of climate change. The yeast grows readily at 37 degrees Celsius and can withstand temperatures as high as 47 degrees Celsius, unlike its closest relatives. It can also survive on hospital surfaces for extended periods and is often resistant to several antifungal medicines at once.

These characteristics make C. auris especially dangerous for immunocompromised people, including some hospital patients and care-home residents. The mortality rate reported in studies of bloodstream infections ranges from 20% to 67%, while the figure is around 52% in many countries. During one European outbreak involving 140 confirmed cases, 41% of affected patients died within a month.

The review places these outcomes in the context of an organism that is difficult to control in healthcare environments, can tolerate elevated temperatures and frequently resists multiple available treatments. The analysis synthesizes published evidence rather than testing an intervention or directly measuring the effect of climate change on infection risk. The review also examines global evidence on how environmental changes affect the spread of fungal diseases, including Cryptococcus gattii, Aspergillus fumigatus and other fungi that are colonizing new regions or frequently developing resistance.

Researchers broadly agree that fungal infections are becoming more significant worldwide, but debate continues over their precise causes and the contribution of individual factors. Schuh and Gokhale propose closer integration of environmental monitoring, climate research, evolutionary biology and medicine, including systematic surveillance of fungi in soil, water, air and hospitals, to detect emerging pathogens before major outbreaks occur. They acknowledge that such early-warning systems would require substantial investment in diagnostics, laboratory capacity and drug development.

The authors expect other closely related species could follow a similar trajectory, making predictive frameworks important for anticipating future fungal threats.

Subject of Research: Environmental and climate drivers of emerging human fungal pathogens, with emphasis on Candida auris

Article Title: Candida auris: A harbinger of further dangerous fungal species?

Article References: Candida auris: A harbinger of further dangerous fungal species?. Original publication (Bibliographic details unavailable.)

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Keywords: Candida auris, fungal pathogens, climate change, antifungal resistance, environmental surveillance, emerging infections, hospital transmission, pathogen evolution, Candida, auris, harbinger, further