How did THE LAST OF US disease start? Is Cordyceps real?

In HBO’s The Last of Us, which is based on the 2013 video game of the same name, a deadly fungal infection called cordyceps nearly wipes out the human race. In the course of one day, September 26, 2003, modern life completely ceased and the population collapsed.

The disease spreads by humans biting each other, but who bit the first person? How did the fungus make the leap from only infecting insects to turning humans into mind-controlled zombies?

What is cordyceps?

This fungus turns people into violent zombies who live only to spread the fungus to other beings. In a terrifying twist, the fungus in the fictional world based on a real fungus that infects ants.

Once an ant is infected with the fungus that was previously known as cordyceps and is now known as ophiocordyceps unilateralis, its brain stops signaling it to meet its own needs and instead wires the ant to spread the fungus.

Other ants can tell when the ants are infected because they start to act disoriented. They immediately take the infected ant away from the group so the fungus won’t continue spreading.

The fungus then grows out of the afflicted ant’s head in a sight that looks like it’s straight from science fiction.

How did cordyceps first infect humans in The Last of Us?

In episode 3 of the first season of The Last of Us Joel explains to Ellie how the cordyceps pandemic started infecting humans.

Ellie suspected that it somehow spread from a monkey to humans, as sometimes happens with viruses. The case with cordyceps in this fictional universe is a bit different.

Cordyceps wasn’t supposed to be able to infect humans the way it infects insects, but somehow the fungus was able to make the leap.

“If you have to get bit to be infected, then who bit the first person? Was it a monkey?” Ellie asks Joel.

Joes replies that no one knows for sure, but the theory is that cordyceps mutated and somehow got into the food supply via flour or sugar.

He then says that the tainted food somehow got into a name brand mass market food like bread that hit the shelves around the same time around the world on Thursday, September 25, 2003. “By Monday everything was gone,” he says.

Could this happen to us in real life?

In the very first episode we see a scientist named Dr. Neuman on a 1968 television show tell the panel that he’s most afraid of a fungal outbreak because fungus can affect the mind. He explains how the mind-altering hallucinogen psilocybin comes from fungi and paints the eerie picture of how fungus can infect an ant and control their brains and behavior.

He then says that fungi can’t survive in hosts with an internal temperature of 94 degrees, but explains that if the earth warms it could make us evolve to have a lower body temperature, which could leave us suspectable to this type of parasitic infection.

“One gene mutates and any one of them could become capable of burrowing into our brains and taking control not of millions of us but billions of us,” Dr. Neuman says. “Billions of puppets with poisoned minds permanently fixed on one unifying goal: to spread the infection to every last human alive by any means necessary.”

This scene was not in the game, but was used a device for the show to explain to the audience the possibility of a fungal pandemic and inspire dread about the potential unthought of consequences of climate change.

This is all very disconcerting, but we have to keep in mind that the way the fungus works in The Last of Us world is still a work of fiction.

Vox spoke to mycologist Charissa de Bekker, who dispels the possibility that a fungal infection like the one depicted in The Last of Us could happen.

She also put to rest the idea that a fungal infection could be spread by biting. Instead, fungus is spread through spores.