If you’re a horror gamer, you already know about the Cordyceps Brain Infection (CBI) which causes the zombie outbreak in Sony’s blockbuster horror game The Last of Us and its just-released sequel. But you may not know that the parasitic fungus itself is based on a real-life “neuro-parasite,” which turns its hosts into zombie-like carriers. If that’s not creepy enough for you, the game’s developers even consulted with an expert on the Cordyceps fungus — and he confirmed they got the parasite’s behavior just about right.
There’s one important difference, of course: the actual Cordyceps — which denotes an entire genus of fungi containing around 400 species — doesn’t select humans as its carriers, but instead targets insects to become “zombified” transmitters of its spores. But don’t breathe easy just yet — this organism’s reproductive cycle is one of the most horrifying in nature, and who knows whether similar organisms might not set their sights on larger hosts.
For example, the species Ophiocordyceps unilateralis mainly targets carpenter ants, attaching itself to an ant’s body and burrowing slowly inward, spreading a spiderweb-like structure called mycelium throughout the still-alive host until nearly half of the insect has been replaced with the fungus, which controls its muscular movements through their own neural network — much like a puppeteer pulling invisible strings.
After a few weeks, the ant’s brain is about the only organ left that the spores haven’t taken over — and this is critical, since Ophiocordyceps needs the ant’s brain to help it guide the nearly-destroyed body to a place where it can effectively spread the spores in another location. Once that spot has been found, the ant bites down on a leaf or branch with a literal “death grip” — using the last of its remaining energy to anchor itself at a higher elevation so the spores can spread. The fungus then sprouts a tentacle-like “fruiting body” from the dead ant’s head:
This may be partly the opposite of the game’s mutant CBI parasite, which attacks the host brain first, then spreads outward… but it’s even more horrifying to know the real-life version leaves the host’s brain intact: basically, the victim is fully aware of being taken over, and can’t do a thing to stop it.
Similar zombie fungi include Ophiocordyceps sinensis, which targets caterpillars as hosts, and Ophiocordyceps humbertii, which infects wasps. The family Clavicipitaceae also targets some insects, but it’s also dangerous to humans, though in a different way: the spores contain a toxins known as ergot, which can trigger intense hallucinations, delirium, and even death. Some historians have theorized that “ergotism” may have been at the center of the mass hysteria that led to the Salem Witch Trials in the late 17th century.