‘The Last of Us’ in real life? Rising temperatures may spread fungal infections

Of course, this is a work of fiction based on the hit PlayStation videogame of the same name. (There’s also a similar plot in the bestselling 2014 novel “The Girl with All the Gifts,” which was adapted into a 2016 movie.) And many scientists on the HBO show note that the average human body temperature of 98.6 degrees Fahrenheit is far too hot for most fungi to survive in the human body. 

But it is suggested on the show that, if the world were to get warmer, then some potentially dangerous fungi could evolve to live in hotter environments, such as the human body. And that’s something a growing body of real-world research suggests could play out in real life — although without creating hordes of zombie-like monsters in the process, of course. 

An estimated 7,199 people in the U.S. died from fungal infections in 2021, according to the Centers for Disease Control and Prevention, compared with just 450 such deaths reported by the CDC in 1969. More than 75,000 people are hospitalized in the U.S. every year with fungal infections. And the number of deaths from fungal infections has increased during the COVID-19 pandemic.

Aside from the human cost, fungal infections also take a heavy financial toll on the country, with direct medical costs estimated at $6.7 billion to $7.5 billion yearly, according to the CDC. The indirect costs from missed work or school, or premature deaths, are guessed to be around $4 billion, with the total financial impact of fungal disease on the U.S. estimated to be at least $11.5 billion, and as high as $48 billion a year.

And the Earth’s climate has warmed since the mid-1800s at a rate not previously seen in the past 10,000 years. NASA notes that the planet’s average surface temperature has risen about 2 degrees Fahrenheit (1 degree Celsius) since the late 19th century, largely from increased carbon dioxide emissions from human activity, with the years 2016 and 2020 being tied for the warmest year on record. 

Meanwhile, deaths from fungal infections are on the rise, as well, according to the research and fundraising organization Global Action for Fungal Infections, which reported fungal infections kill more than 1.6 million people a year worldwide. The organization adds that more people die of fungal diseases than either tuberculosis or malaria.

What’s more, a Duke University study published in the journal Proceedings of the National Academy of Sciences in January grew 800 generations of Cryptococcus deneoformans fungi (which can cause severe infections in people, particularly those with weakened immune systems), finding that higher temperatures may indeed push these fungi to evolve faster in order to survive hotter environments. 

“As fungi are exposed to more consistent elevated temperatures, there’s a real possibility that certain fungi that were previously harmless suddenly become potential pathogens,” Peter Pappas, an infectious-disease specialist at the University of Alabama at Birmingham, told The Wall Street Journal. 

In other concerning fungi findings: 

The World Health Organization released its first-ever list of health-threatening fungi last October. It highlighted 19 “fungal priority pathogens” that it said represent “the greatest threat to public health” because they are becoming more common and more resistant to treatment. WHO noted that these invasive fungal infections pose the greatest risk to severely ill patients and people with weakened immune systems, such as those with cancer, HIV/AIDS, organ transplants, chronic respiratory disease and those suffering post-primary tuberculosis infections. 

“Emerging from the shadows of the bacterial antimicrobial resistance pandemic, fungal infections are growing, and are ever more resistant to treatments, becoming a public health concern worldwide” said Dr. Hanan Balkhy, WHO Assistant Director-General of Antimicrobial Resistance, in a statement. The WHO report noted that fungal infections receive little attention and resources, so there’s a scarcity of high-quality data on how many people suffer fungal infections, as well as how fungi may be developing resistances to the few treatments that are available. 

Most people are familiar with antifungal medications that treat yeast infections, athlete’s foot and ringworm. But the Food and Drug Administration has only approved four classes of antifungal medications for invasive infections, The Wall Street Journal notes, and most of these are toxic, even at low doses. This is because fungi cells are more similar to human cells than microbes like bacteria, so the medications that are toxic to fungi are also often toxic to humans. And there are no approved vaccines for fungi. 

So what can we do? The CDC notes that health professionals should continue to raise awareness about fungal diseases to increase early diagnosis and proper treatment. And public health officials need to develop new systems and expand existing systems for fungal disease surveillance and treatment.

As for the rest of us, here’s a CDC list of the most common types of fungal infections in humans, including their symptoms and how they are treated. Don’t panic — fungi are common in the environment, and people breathe in or come in contact with fungal spores every day without getting sick — but be aware that there are some people who might be at greater risk of becoming severely ill. Learn about fungal infections so that you and your doctor can recognize them early, and hopefully get treatment before suffering any severe complications.