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‘The Last of Us’ Cordyceps Brain Infection Is Realer Than You Think

Ellie standing wary with a gun in the woods

Yes, the disturbing cordyceps brain fungus from The Last of Us is a real thing, y’all. No, it isn’t some gross alien being made up by H.R. Giger or a fictional virus made up by The Walking Dead’s Robert Kirkman. It was not adapted from a best selling novel by the King of Horror himself, Stephen King. It was instead dreamed up by the Queen of Horror. Who am I talking about? Mother Nature, the scariest there ever was.

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Mother Nature apparently had a bone to pick with the rest of the creatures on Earth with this one. Apparently, flesh-eating bacteria and the very idea of tapeworms just weren’t enough to make life miserable for other living things. Okay, so the cordyceps fungus is a fungus that (good news) only infects little gross bugs. The bad news is that there are over 600 different species of cordyceps, and oh god, what if it’s only a matter of time before one of those species can infect us? What is the virus in The Last of Us, and how does cordyceps infect ants?

So here’s what cordyceps does to poor, gross little bugs—in this case, ants. The cordyceps fungus gets inside of a poor little ant and infects it. It then does some complicated science shit in order to take control of the ant’s body and compels it to leave the safety of its nest and climb up onto the stalks of plants, to an altitude that is ideal for fungal growth. The the fungus causes the ant’s mandibles to clamp down onto the stalk, and then then fungus bursts out of the ant’s head like a cranial Alien and shoots off spores in order to infect the rest of the any colony. And that is fucked up.

How did this little fungus even evolve to do this? Most living things are like, “I’m just gonna eat stuff or sit in the sun or grow on stuff to live,” but this little fungus was like, “Screw that. I’m living life on hard mode,” and decided to come up with the most batshit lifestyle in order to not conform to the boring standards of other living things. And honestly, I respect that. It’s pretty metal. But it also makes me deeply uncomfortable. Apparently, it also made the people at Naughty Dog deeply uncomfortable, too—so uncomfortable, in fact, that they decided to create a horror game around the concept. And this is where The Last of Us comes in.

In the world of The Last Of Us, all of my worst fears are realized. The cordyceps fungus does indeed find a way to attach itself to human beings, and it uses its totally metal and non-conformist lifestyle to make life hell for everyone else. The cordyceps fungus in the game originates from crops imported from South America (where the ant-brain cordyceps also happens to be located) and begins to spread across the world.

When spores of the fungus are inhaled, ingested, or absorbed through wounds, it causes the host’s mental faculties to quickly deteriorate. The infected person then basically turns into a 28 Days Later-style “runner zombie” and tries to single-mindedly bite uninfected people in order to spread the fungus. It is not known if the infected are “conscious” in this state, but judging by the fact that many of them wail and scream and cry, one could make the hypothesis that they can’t control their bodies but are indeed aware of their actions.


Sorry. Had to get that out, but don’t worry; it gets worse. After years of infection, the fungus eventually begins to grow outside of the human body just like it does with the ants. Hard fungal growths erupt from the brain and pierce the skin of the victim, and then the growths eventually cover the victim’s eyes. This turns the victim into something called a “clicker.” which is a type of infected that uses echolocation in order to hunt its prey. EW.

Clickers live in dark, dank, sunless places and make clicking sounds in order to help find and infect any living thing unfortunate enough to stumble across them. Clickers are also incredibly strong and can easily overpower a human being. They are also immune to headshots due to the nasty, semi-bulletproof fungus, and can generally only be dispatched with high powered ammo or close-range shotgun blasts. And these bastards aren’t even the final stage of infection.

The final stage of infection takes place a decade after infection. The victim’s body is head to toe covered in fungal plates, and the creature has increased size and hulk-like physical strength. At this stage of infection, these creatures are called “bloaters” and barely resemble human beings at all. They are able to take multiple shotgun blasts to the face and keep on coming, and they usually require multiple people to take down. Currently, these bastards are rare, as the fungus hasn’t been around for that long and infected are often killed before reaching this stage. However, it should be noted that after enough time has passed, every single infected on Earth will become a bloater if left unchecked. And if that happens, humanity is seriously screwed.

There are other strange exceptions to the stages of infection. Most notably, in The Last of Us 2, the main character, Ellie, encountered a creature known as a “Rat King” in a hospital in Seattle. The creature was not one infected, but a mass of infected people that had somehow, to put it in scientific terms, glommed onto each other and formed a sort of super organism that was even stronger than a bloater. The creature was a tangled mass of limbs stuck onto a body, but some of those limbs were actually attached to other bodies that could fall off the Rat King and attack independently. This seems to suggest that the Rat King is actually a colony of cordyceps that (like fungi in real life) is made of up individuals that have glommed together and can now communicate with each other and act as one. And that is SO GROSS.

There is a bright side, however. Some people, for scientific reasons, have an immunity to the cordyceps infection. Ellie is one of those people. She has the fungus in her brain, but it hasn’t taken over her body. This sounds like it would be dope because it means that maybe a potential treatment or cure could be developed by studying Ellie, but in reality the only way it can be done is by surgically messing around with Ellie’s brain and killing her in the process. Joel respectfully disagrees with the medical professionals who are of the opinion that killing Ellie and studying her is the best course of action, and he voices that disagreement by shooting them in the face. According to Joel, mysteries like the cordyceps virus are better left unsolved.

(featured image credit: Naughty Dog)

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Jack Doyle
Jack Doyle (they/them) is actually nine choirs of biblically accurate angels in crammed into one pair of $10 overalls. They have been writing articles for nerds on the internet for less than a year now. They really like anime. Like... REALLY like it. Like you know those annoying little kids that will only eat hotdogs and chicken fingers? They're like that... but with anime. It's starting to get sad.

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