According to HBO’s zombie apocalypse series The last of us, the end of humanity comes via the tentacles of a brain-infecting fungus called cordyceps.
As with so many terrifying storylines, the germ-gone-feral depicted in the hit series has roots in the real world.
Cordyceps mushrooms are true organisms that are most at home in warm, humid climates. They take over the minds of ants as well as some spiders, moths, crickets and other arthropods, but fortunately not humans.
“The fungus attacks insects that live in the ground or soil,” said Rebeca Rosengaus, associate professor and behavioral ecologist at Northeastern University. “Ants are one of them, but there are also grasshoppers, spiders, locusts.”
The official name of Cordyceps is Ophiocordyceps unilateralisand yes, scientists call it the “zombie-ant mushroom.” It doesn’t mean the end of humanity, but it certainly means a grisly end for the creatures it infects.
Here’s how it works: the ant (or other arthropod) emerges innocently from its nest, searching for food and blissfully unaware that cordyceps spores are raining down from a nearby tree, stem or branch.
The spores cling to the ant (or other creature), releasing digestive enzymes to break down the insect’s cuticle (hard outer shell). Threadlike growths, known as mycelia, begin to grow inward and eventually take over the insect’s brain, which begins to produce neurotransmitters that affect brain function. The transformation is complete: the ant begins to stumble and convulse, acting in a way that benefits the cordyceps.
“The fungus basically hijacks the brain so that the ants stop doing what ants do and start doing what the fungus wants it to do, which is climb up the trunk of the tree,” Rosengaus said. Once they reach the treetops, the ants bite the stem or leaf in what is called a death grip.
“It’s the last thing they do before the fungus starts growing from the ant’s neck or head,” Rosengaus said.
Ants die within six hours of infection, then two to three days later a the fungal stem emerges by the neck. Then the spores start raining down again and the cycle repeats.
That’s life, at least for arthropods.
“Like many organisms on the planet, it does what it needs to do to replicate and continue to reproduce,” said Dr. Scott Roberts, associate medical director of infection control at Yale School of Medicine.
Could this happen in humans?
The last of us is real life for ants but not for humans — at least not yet, Rosengaus said, though she wouldn’t rule it out altogether. “The fact that we don’t have a pathogen capable of coming up with this strategy to hijack our minds doesn’t mean it’s not a possibility at some point.”
For now, however, this is unlikely to occur in humans. “One of the reasons for that is that humans are warm-blooded,” Roberts said. “Most fungi and molds do not grow well in high temperature environments.” Humans, who have a body temperature of 98.6 degrees Fahrenheit, are definitely inhospitable.
“The show’s creators took a very special moment in nature and romanticized it,” Roberts added. “It’s a popular and great TV show, but it’s not really a viable or realistic representation of what could happen.”
“I don’t think we should be worried,” said William Schaffner, an infectious disease expert at Vanderbilt University. “A fungus is a much higher order, much more complicated germ than a virus, so it would be a much more complicated phenomenon for this fungus to jump from species to species.”
Which is not to say that humans cannot be infected by organisms that commonly infect other species.
“We have zoonotic infections,” Roberts said. Mpox is a good example. The same goes for COVID-19, which originates from the SARS-CoV-2 virus. “Often viruses and sometimes even fungi can be of another species and jump to other humans, but this usually requires gradual jumps back and forth. [between humans and animals].”
Climate change also introduces new hazards, including new fungi. One is one type of yeast called white ears.
The the body’s adaptation to warmer temperatures is believed to be the reason why it now has a better chance of being able to survive in the human body. (This is also the reason The last of us writers use to explain why cordyceps can infect people.)
While white ears gravitates around your skin, it can cause bloodstream infections and is often spread in hospitals and other health care facilities.
“If you are healthy, it will stay on your skin and [even] go away, but if you have lines and catheters and you’ve had surgeries, it can cause infections in the wounds,” Roberts said. These infections can spread not only to the bloodstream, but also to different organs, such as the brain and heart.
“It’s a type of candida species that emerged with climate change,” Roberts said. “It’s possible that other fungi and molds are evolving to survive and reproduce in warmer climates.”
white earswhich was first recognized only about 10 years ago, is already multi-drug resistant. It also spreads from person to person, unlike other types of mold or fungus that more often come from the environment, Roberts said.
As with most mushrooms, if you are healthy, white ears not likely to cause harm. However, if you are immunocompromised or in poor health, they can cause serious and even life-threatening infections.
Separating fact from fiction
There’s another entity hijacking our brains right now: science fiction disinformation masquerading as fact.
As long as you realize The last of us and other shows are fiction, there is no harm.
“For decades, science fiction writers have taken basic ideas to extremes. That’s part of the fun,” Schaffner said. “As wonderfully rich and extraordinary as real science is, there are real biological limits, and this would be one. When it comes to real life, listen to public health. We will link you to reality.
It’s not like we have to look for things to fear. “If you asked me if this fungus or SARS-CoV-2 would end us, a hundred times out of a hundred, I would say SARS,” Roberts said.