Nav: Home

Is deadly Candida auris a product of global warming?

July 24, 2019

A drug-resistant fungus species called Candida auris, which was first identified ten years ago and has since caused hundreds of deadly outbreaks in hospitals around the world, may have become a human pathogen in part due to global warming, according to three scientists led by a researcher at the Johns Hopkins Bloomberg School of Public Health.

C. auris was first isolated from the infected ear of an elderly patient in Japan in 2009, and within a few years caused hospital outbreaks in many different parts of the world. Between 30 and 60 percent of patients diagnosed with invasive C. auris infection have died. C. auris's sudden emergence as a human-infecting pathogen is as mysterious as it is alarming, for it happened simultaneously among several distinct families or "clades" of this fungus that exist separately on different continents.

The scientists, in their paper published July 23 in the journal mBio, suggest that this global transformation of C. auris into a deadly pathogen may be due to global warming, which could have forced C. auris clades around the world to adapt to higher temperatures. That adaptation would have made it easier for this microbe to infect humans, whose relatively warm core temperature of 98.6 degrees Fahrenheit (37 degrees Celsius) normally serves as a "thermal barrier" against fungal invasion.

"We think that C. auris may be the first example of a fungal species that has jumped the thermal barrier due to adapting to global warming," says lead author Arturo Casadevall, MD, PhD, the Alfred and Jill Sommer Professor and Chair of the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Bloomberg School.

Microbiologists estimate there are more than a million fungal species. However, most known species are adapted for living in soils, on trees, and in other places in the natural environment, where temperatures on average are much cooler than mammalian core temperatures. Only a tiny proportion of fungal species can infect humans, and dangerous internal infections with fungi typically occur only in people with very weak immune systems.

Casadevall, a Bloomberg Distinguished Professor, warned in a paper in 2010 that global warming could trigger the emergence of many more fungal pathogens. In the new paper, he and his colleagues hypothesize that C. auris is the first of these.

Analyzing the temperature range for C. auris and a few dozen species that are its nearest fungal relatives, the scientists found that the new pathogen can grow at higher temperatures than most of these near-relatives, hinting that it may have acquired its thermal tolerance only recently. They also cited a previous finding from Casadevall's laboratory that some other fungal species in a large culture collection had begun to adapt to global warming by increasing their tolerance for higher temperatures.

Proving that global warming spurred the emergence of C. auris as a human pathogen will be difficult, but Casadevall and colleagues argue that this possibility--and the possibility that other new fungal pathogens will emerge--must be borne in mind as the global average temperature continues to rise.

"Right now fungal diseases are usually not reportable," Casadevall says. "So we need better surveillance of these infections in humans--and even in other mammals, where the first warnings of new fungal pathogens might occur."

C. auris strains usually have considerable resistance to antifungal drugs, and some resist all the usual treatments. How this resistance arose is another mystery--many scientists suspect that the widespread agricultural use of fungicides was the key factor. In any case, it underscores the need for better reporting of serious fungal infections and for new antifungal drugs, says Casadevall.
-end-
"On the Emergence of Candida auris: Climate Change, Azoles, Swamps, and Birds" was written by Arturo Casadevall, Dimitrios Kontoyiannis of the University of Texas MD Anderson Cancer Center, and Vincent Robert of the Westerdijk Fungal Biodiversity Institute in the Netherlands.

Johns Hopkins University Bloomberg School of Public Health

Related Global Warming Articles:

A new study provides a solid evidence for global warming
The new study allows a more accurate assessment of how much heat has accumulated in the ocean (and Earth) system.
Global warming hiatus disproved -- again
UC Berkeley scientists calculated average ocean temperatures from 1999 to 2015, separately using ocean buoys and satellite data, and confirmed the uninterrupted warming trend reported by NOAA in 2015, based on that organization's recalibration of sea surface temperature recordings from ships and buoys.
Report reassesses variations in global warming
Experts at the European Centre for Medium-Range Weather Forecasts (ECMWF) have issued a new assessment of temperature trends and variations from the latest available data and analyses.
Clouds are impeding global warming... for now
Lawrence Livermore National Laboratory researchers have identified a mechanism that causes low clouds -- and their influence on Earth's energy balance -- to respond differently to global warming depending on their spatial pattern.
Global warming's next surprise: Saltier beaches
Batches of sand from a beach on the Delaware Bay are yielding insights into the powerful impact of temperature rise and evaporation along the shore that are in turn challenging long-held assumptions about what causes beach salinity to fluctuate in coastal zones that support a rich network of sea creatures and plants.
More Global Warming News and Global Warming Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#534 Bacteria are Coming for Your OJ
What makes breakfast, breakfast? Well, according to every movie and TV show we've ever seen, a big glass of orange juice is basically required. But our morning grapefruit might be in danger. Why? Citrus greening, a bacteria carried by a bug, has infected 90% of the citrus groves in Florida. It's coming for your OJ. We'll talk with University of Maryland plant virologist Anne Simon about ways to stop the citrus killer, and with science writer and journalist Maryn McKenna about why throwing antibiotics at the problem is probably not the solution. Related links: A Review of the Citrus Greening...