The fungus from “The Last of Us” isn’t real, but the threat of fungal parasites to human health is growing
(CNN) — In the HBO series The Last of Usthe characters identify the zombies among themselves by the fungi that sprout from their bodies, and the fungal parasites manipulate humans to infect the communities around them.
In real life, the species of fungus that inspired the story, the ophiocordyceps, infects insects and does not cause problems in people. (HBO, like CNN, is a unit of Warner Bros. Discovery.)
However, the threat from pathogenic fungi is growing, experts say, and may become much worse in a hotter, wetter and sicker world.
“We are always surrounded by fungal spores. We have lived with them since we made beds on the savannah 500,000 years ago, before we even evolved into modern humans. And we have had to adapt this exquisite immune system that we have to defend ourselves against fungal spores. spores, because many of them are potentially pathogenic,” explains Dr. Matthew Fisher, Professor of Medicine at the University of California’s School of Public Health. imperial college londonwhose research focuses on emerging fungal pathogens.
“Fungi are only looking for food sources, and in the eyes of many saprotrophic fungi, we are simply food,” he added. (Saprotroph describes an organism that feeds on dead organic matter.)
Many millions of fungi are good for the environment, but a few hundred can cause disease in humans.
Millions of infections a year
The scientists continually discover new fungi (last year they found four), but not all are a threat to humans.
Of the nearly 4 million species of fungi, the scientists have only identified 300 as human pathogens capable of causing disease.
In any given year, more than a billion people suffer from what Microbiology Society considered “superficial” fungal infections.
athlete’s foota scaly rash that can be itchy or stinging; thrush, white lesions that develop on the tongue or on the inside of the cheeks; and even dandruff they are largely caused by one of these superficial fungal infections. They are irritating, but luckily the treatments continue to work on them.
Some infections can be much more serious, even life-threatening.
According to the Society for Microbiology, Every year around 1.5 million people die in the world. because of them, with few if any effective treatments.
Last year, the World Health Organization (WHO) declared that it considers pathogenic fungi a “major threat” to public health and, for the first time, posted his list priority of the 19 types the world should watch.
One of the four most critical species on the WHO list is the cryptococcus neoformans, a pathogenic yeast that lives in the soil. People can inhale fungal cells, and most do not get sick. But in those with suppressed immune systems, it can affect the lungs and spread to the nervous system and blood. Over the years, this fungus has become resistant to some treatments.
Another is the Candida auris, a yeast that can remain on medical surfaces and equipment and spread rapidly from person to person. has caused a increasing number of hospital outbreaks around the world, a threat that grew even more during the covid-19 pandemic.
According to the CDC, this may be due in part to changes in routine infection control practices. The infection can affect the heart, central nervous system, eyes, bones, and internal organs. It is resistant to many kinds of antifungal treatments, but can sometimes be treated with antifungal drugs called echinocandins.
He Apergillus fumigatus, a mold that can be found almost everywhere, can cause lung disease in people with weakened immune systems. It could also cause allergic reactions or lung infections that could worsen and move to other organs. It has shown increasing resistance to antifungals, according to the WHO, thanks to the widespread use of azole fungicides to prevent its spread in crops.
The fourth pathogen, Candida albicans, is another yeast that is often part of a healthy human microbiome. It lives in the mouth, intestines and skin. Bacteria in the body keep it in check, but if the system is out of balance, the yeast overgrows and develops into a yeast infection, diaper rash, thrush, or other condition. It can also develop into a serious infection that affects the blood, heart, central nervous system, eyes, bones, and internal organs.
There are no vaccines for any of the four fungal infections on the critical list.
Who is most at risk?
Generally, Fisher says, our bodies are pretty good at protecting us against fungal infections, but “it opens holes in our immune system.”
“Then we can have fatal consequences,” he said.
People most at risk for a serious fungal infection are those with underlying conditions such as HIV, cancer, or diabetes, and those with compromised immune systems due to age, disease, or the drugs they take.
Other people are vulnerable to the more serious consequences of fungal infections because they do not have access to the most common medicines in the West. For example, cryptococcal meningitis is one of the leading causes of death among HIV-positive people in sub-Saharan Africa because they do not have access to treatment, according to studies.
Why do fungal threats grow?
The number of serious fungal infections has increased in part due to the increasing number of immunosuppressed people, indicate studies.
“What is changing is that more and more exposed people have these high risk factors. We have aging populations and we use a lot of chemicals in the environment that force fungi to adapt, and our clinical antifungals are degrading because of resistance. antimicrobials,” explains Fisher.
More occasional fungal infections have also occurred during the covid-19 pandemic, just as after flu epidemics, according to Dr. Matthew Kasson, a mycologist at the West Virginia University.
“Viruses suppress the immune response, and some of the drugs we use to fight viruses also make it easier for fungi to invade,” he explains.
A black fungus killed thousands of people in india in 2021, and 85% of them were covid-19 patients.
Fisher noted that some fungi also seem to “appear out of nowhere” and “spread around the world quite silently, causing silent pandemics,” such as Candida auris.
Furthermore, the climate crisis has exacerbated the spread of fungal infections.
“The world is getting hotter and wetter. That’s just going to mean there’s a bigger mold spore load,” Fisher says.
what to do
WHO encourages countries to improve their diagnostic capacity for fungal infections and to increase surveillance. It also recommends that more money be spent on research, drugs, and tests for these infections. Currently, fungal infections receive less than 1.5% of all funds devoted to infectious disease research, according to the WHO.
It’s hard to develop treatments against fungi because, in the words of Matt Nelsen, a researcher at the Field Museum in Chicago, “animals and fungi are each other’s closest relatives.”
“We share a lot of biochemical similarities, so when we’re trying to kill the fungus, we have to be careful not to kill ourselves as well,” he explains.
One of the best defenses against fungal infections is to keep your immune system strong.
Fisher advises parents to let children play a lot outside so they are exposed to a good variety of fungi that help them develop a healthy immune system. Houses should also be well ventilated and free of moisture.
Kasson believes that the attention generated by The Last of Us and Other Shows means “mushrooms are having their moment,” though he hopes that’s not being overstated.
when the movie was released Shark, there was an increase in shark hunting. In fact, sharks were nearly hunted to extinction.
Millions of mushrooms are good, Kasson notes. They decompose wood, and can be used in food and in human medicine.
“Yes, fungal infections are a serious problem, and I think it’s going to get worse unless we start to really appreciate those connections between how we manage crops, how we manage human disease, how we manage wildlife disease. They’re all interconnected. “, he claimed. “The sooner we realize this, I think, the sooner we can find solutions that help everyone involved.”