Sunday January 19, 2020

Study: Global Temperatures May be Responsible for Rise of Deadly Fungal Disease

Though only 715 people in the United States have contracted the new fungal infection so far, scientists say it may be an indication of what's to come

fungal disease, global temperatures
FILE - This undated photo shows a CDC technician making notations on culture plates in which fungal colonies had been grown. The fungus Candida auris has spread to more than 30 countries in the past decade. VOA

The first fungal disease linked to rising global temperatures may have emerged, suggests a study published in the scientific journal mBio. Though only 715 people in the United States have contracted the new fungal infection so far, scientists say it may be an indication of what’s to come.

Three unrelated variants of deadly Candida auris cropped up simultaneously in South America, Asia and Africa, and it has spread to more than 30 countries in the past decade.

The fungus, which is difficult to treat, can be life-threatening in people with weakened immune systems. The U.S. Centers for Disease Control and Prevention (CDC) said C. auris has been found to be resistant to all three of the most common antifungal drugs, and more than a third of people afflicted with invasive cases of the fungus die.

Mild fungal maladies like athlete’s foot are common, but severe fungal infections are relatively rare in healthy individuals. We are guarded from fungal infections by our strong immune systems and high body temperatures. Knock down one or both of those protective pillars, however, and humans start to look like a good host for opportunistic fungi.

Dr. Arturo Casadevall, a microbiology professor at Johns Hopkins University and lead author of the paper, suggested nearly 10 years ago that fungi would become more heat-tolerant as Earth became warmer, causing humans to lose the advantage that our high body temperatures provide. He said C. auris may be the first example — and it’s unlikely to be the last.

fungal disease, global temperatures
U.S. public health officials are urging doctors and nurses around the world to be on the lookout for a highly drug-resistant yeast strain called Candida auris. (Photo courtesy of CDC). VOA

Heat-tolerant fungus

The researchers compared the heat tolerance of C. auris to that of similar species. While most of the species they considered don’t multiply above 35-37°C (95-98.6°F), C. auris can survive temperatures of up to 42°C (107.6°F).

That’s a problem for people because “we have very little ability [to adapt],” said Casadevall. “We can’t raise our temperature and walk around with a high fever all the time. But these organisms have the capacity to adapt to change, and for them, this change is happening gradually, because they can replicate every couple of hours.”

Alone, C. auris’ tolerance of high temperatures isn’t enough to prove that its rise is the product of climate change, since it isn’t clear how long ago the fungi developed their resistance to high temperatures. The researchers acknowledge that climate change is likely just one of many factors that led to its emergence.

“When it comes to the origins of Candida auris, it’s a complete mystery about where it came from still,” said Dr. Brendan Jackson, leader of the epidemiology team of the CDC’s fungal diseases branch, who was not involved with the research. “It’s clear there are huge environmental changes going on in the world, and for a fungal organism that has just come onto the scene within the last decade in multiple places in the world, it does make you think that something could be happening on a large environmental scale.”

In order to determine how large a role climate change played, the researchers suggest more careful analysis of C. auris’ ability to tolerate high temperatures. For example, if early outbreaks are less heat-tolerant than later outbreaks, that could indicate that the fungi are rapidly adapting to warmer temperatures.

Fungal disease
Fungus can impair the immune system. Pixabay

Looking ahead 

Casadevall noted that C. auris has mostly affected people with weakened immune systems, which could mean that while the fungus has adapted to high temperatures, it still isn’t very good at infecting people. On the other hand, he added, it’s possible that there are other fungi that are highly infectious but can’t grow in higher temperatures yet.

If climate change created one new infection, Casadevall said, “we can’t prevent it from happening again. This is likely something that humanity is going to have to deal with. I do think that we could be better prepared if there were more monitoring of fungal diseases, more research into how fungi cause disease and more antifungal drugs.”

ALSO READ: Many US Cities Lack Data to Measure Greenhouse Emissions Progress: Report

Jackson said the CDC has increased its efforts to inform the public about the seriousness of fungal infections, and new antifungal drugs are under development. Despite the increasing number of cases around the world, he emphasized that there’s no cause for alarm since C. auris poses little to no threat to healthy individuals.

“There’s a lot of fear that comes with an emerging pathogen like this,” said Jackson. “But this is affecting the sickest of the sick. I think it’s something to be on top of, but the average person does not need to be concerned about this in their daily life.”  (VOA)

Next Story

2000-2019: The Hottest Decade Measured

US Experts: Last Decade was Hottest Ever Recorded

Hottest decade global warming
Last year was the second hottest ever due to global warming. Pixabay

The last 10 years were the hottest decade ever measured on Earth, last year was the second warmest ever and NASA says “you haven’t seen anything yet.”

The National Oceanic and Atmospheric Administration said Wednesday that the average global temperature in the 2010s was 14.7 degrees Celsius, with eight of the 10 hottest years ever recorded.

Parts of Africa, Asia, Australia, Europe and South America had record-high temperatures in 2019. Alaska’s average temperature was above freezing for the first time in recorded history.

Hottest decade global warming
People walk outside of the COP25 climate talks congress in Madrid, Spain. VOA

Many climate scientists who have seen the study said there was no other explanation for the record-breaking warming than human activity.

“This is going to be part of what we see every year until we stabilize greenhouse gases,” said Gavin Schmidt, head of NASA’s Goddard Institute for Space Studies. “We crossed over into more than 2 degrees Fahrenheit warming territory in 2015 and we are unlikely to go back. This shows that what’s happening is persistent, not a fluke due to some weather phenomenon.”

Also Read- Amazon CEO Jeff Bezos Roasted for Donating Pittance Towards Australian Bushfires Relief

Experts say natural causes of a warmer atmosphere, including more heat from the sun and climate variations, are not big enough to explain the long-term temperature rise.

For those who still question global warming, the scientists say all one has to do is look at melting ice sheets, more powerful storms, floods in some parts of the world and drought in others as clear evidence. (VOA)