A dangerous fungus known as Candida auris has cropped up simultaneously in far corners of the world — atypical behavior for a fungus, which usually radiates from one location.
That development, and signs of the pathogen’s unusual tolerance of heat in those areas, leads a group of scientists to theorize that global warming is in part responsible for the recurrence of the drug-resistant fungus that poses the biggest risks for already sick hospital patients or older residents in long-term care facilities. Fungal infections can be the toughest for doctors to treat.
“The most enigmatic aspect of the rise of Candida auris as a human pathogen is that it emerged simultaneously on three continents, with each clade, a group of organisms believed to have evolved from a common ancestor, being genetically distinct,” reads the abstract from the study, conducted by researchers at the Johns Hopkins Bloomberg School of Public Health. Their results were published this week in the American Society for Microbiology’s journal mBio.
“Although new pathogenic fungal species are described regularly, these are mostly species associated with single cases in individuals who are immunosuppressed,” the researchers said. “In this study, we used phylogenetic analysis to compare the temperature susceptibility of C. auris [a pathogen named when it was discovered 10 years ago in a Japanese patient with an ear infection; auris is Latin for “ear”] with those of its close relatives and to use these results to argue that it may be the first example of a new fungal disease emerging from climate change, with the caveat that many other factors may have contributed.”
Human-induced climate change is anticipated to warm the earth by several degrees in the 21st century, which will reduce the magnitude of the gap between ambient temperatures and the body temp of mammals. Fungi generally prefer cooler surroundings, such as mushrooms on a forest floor and the typically cooler nail beds on humans relative to other areas of the body.
But C. auris, so far largely resilient to drugs, has been found to survive in a hotter environment.
“Consequently, there is concern that higher ambient temperatures will lead to the selection of fungal lineages to become more thermally tolerant, such that they can breach the mammalian thermal restriction zone… and can be rapidly adapted to growth at higher temperatures by thermal selection…,” the researchers wrote.
What’s more, “given the capacity of fungal species to adapt to higher temperatures and the fact that many fungal species that are currently nonpathogenic species are likely to have the necessary virulence attributes by virtue of their survival in soils, we previously hypothesized that climate change would bring new fungal diseases,” they said.
About a third of patients with a C. auris infection die, physicians told NBC in this report.
A separate recent report cited by the Centers for Disease Control also suggested climate change has played a role in the emergence of drug-resistant fungal infections.
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