The Last of Us: Is Cordyceps Brain Infection Real

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Infected in The Last of Us
Credit: HBO Max

The live-action adaptation of the popular video game, The Last of Us, has finally been released on HBO Max and it did not fail to disappoint its avid fans. Even those who are just discovering the show now are getting hooked to the story.

Set in a post-apocalyptic world, the story of The Last of Us follows as Joel (played by Pedro Pascal) and Ellie (played by Bella Ramsey) journey against the infected. But what caused the other humans to be this way? And what do we need to know about the viral outbreak in the show?


What Is the Brain Infection Caused by in The Last of Us?

Infected person in The Last of Us
Credit: HBO Max

Both the video game and the live adaptation introduces us to the Cordyceps infection that affects the brain. Once a host is infected, it's only a matter of time before the parasite attacks the brain and turns humans into rabid monsters.

The Last of Us shows us what happens to human civilization when things get out of control and with the Fireflies' resistance movement to fight against the FEDRA (Federal Disaster Response Agency).

The outbreak was caused by a mutated strain of the Cordyceps fungi, which develops in the brain. Cordyceps Brain Infection (CBI) spreads via airborne spores or when someone gets bitten by an infected person. The symptoms of the infection starts taking effect in two days.

The Last of Us bite
Credit: HBO Max

Once the parasite enters the body, it starts growing as its host is still alive. The scary part about this infection is that it mutates several times in the body, which causes different infection stages and the host becomes hyper-aggressive. Ultimately, the host dies when it reaches late stage infection.

What Are the Symptoms of Cordyceps Brain Infection?

The Last of Us infected
Credit: HBO Max

Those who were bitten by an infected person can start seeing symptoms in as little as 5 to 15 minutes. The infected starts coughing, having muscle spams, slurred speech, and mood changes. In 2 to 8 hours, the infection starts taking over the torso and the arms. And in 12 to 24 hours, it starts affecting the legs and the feet.

In the video game, CBI has four infection stages, which include the following:

  • Runners
  • Stalkers
  • Clickers
  • Bloaters

These stages are named after the different qualities exhibited by the infected as the fungus mutates throughout the body.

Where Does the Cordyceps Fungi Come From?

Bella Ramsey as Ellie in The Last of Us
Credit: HBO Max

In the game, the Cordyceps fungus comes from infected crops that caused its spread to humans. One thing different in the show, however, is that the illness seems to spread through infected wounds. But since co-creator Craig Mazin did not want to make the cast wear gas masks, they won't be including the threat of airborne spores.

In an interview with Collider, Mazin said:

"The game had spores in the air and people had to wear gas masks, and we decided, early on, that we didn't wanna do that for the show. Eventually, those conversations led us to these tendrils. And then, just thinking about how there's a passage that happens from one infected to another, and like fungus does, it could become a network that is interconnected. It became very scary to think that they're all working against us in this unified way, which was a concept that I really liked, that got developed in the show."

Is Cordyceps Brain Infection Real?

Pedro Pascal as Joel in The Last of Us
Credit: HBO Max

Although Cordyceps is a real fungus, CBI is not something that humans have to worry about. Instead, the fungus preys on insects.

One of the things that led to the success of The Last of Us as a video game is that it has a very interesting storyline. And this is because the creator of the game actually consulted with a real expert in Entomology & Biology from the Center for Infectious Disease Dynamics (CIDD), Dr. David Hughes.

In real life, there are hundreds of species of the fungus. The one that inspired the video game is the Ophiocordyceps unilateralis. As explained by Dr. Hughes, the fungus actually lives inside the bodies of insects and does not affect its brain. Still, the fungus forces the ant to go up, bite on a leaf, and hang suspended until it dies.

Pedro Pascal as Joel in The Last of Us
Credit: HBO Max

Once the ant is dead, a long stalk grows from the body of the host and releases infectious Cordyceps spores below. As such, this fungi has been known to wipe out entire ant colonies.

Dr. Hughes was asked by The Huffington Post of the chances that the Cordyceps fungi will affect humans too. He answered:

We already eat this fungus medically since it has certain properties we like. It is very expensive because of this. These fungi have been known to jump between Kingdoms of life (so from fungi to insects to plants). Jumping is not the problem- opportunity is. So, long as we don't start eating ants from forests we are fine. But we eat chimps from forests (and other bush meat) and so get their diseases (AIDS).


Catch The Last of Us as more episodes get released on HBO Max. Episodes get released every Sunday until March 12.

You can watch the trailer for the upcoming episodes here:


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