Cordyceps

   When Seeg started playing The Last of Us, it took me a while to actually catch any mention of the name of the infection that was spreading across the human race, but when I finally did, I was surprised. Cordyceps. The reason I was surprised was because I'd heard of that a few years ago, and I couldn't help thinking that the game had a little more credibility because of it.

   Cordyceps are real. In fact, it's abundant. It's a fungus that controls the mind, drives the victim to death, then starts growing from the inside out, bursting through their heads and bodies to release spores into the air to 'infect' others.

   It's real. Except it only affects insects. In fact, it's extremely specialised, with one type of cordyceps for each subtype of insect, and it keeps the insect population under control.

   An ant, for example, will get infected by taking in the spores. The fungus will begin to grow and take control of their mind, forcing them to climb up into high areas, and once it's satisfied, it makes the ant clamp onto the branch, grass, whatever it is with its mandibles, and it will die there. The fungus will continue to grow inside it and burst out from its body to release new spores, and those spores will then be taken in by another of the same type of ant. It's so deadly to them, and ants are so clever, that if any of the ants realise that one from their colony is infected, they will carry the infected individual as far from the colony as they can to keep the spores from affecting them when it dies.

   In The Last of Us, the cordyceps is transmitted by spores, and the fungus is taken in by humans and grows on the brain, taking control of their mind. As the infection grows, they lose all sense of themselves and their heads become covered in fungus. But it can also be transmitted by saliva - yes, bites. I don't like that, it's too zombie like and it doesn't work that way, but at the same time they have to make threats more mobile in the game. You do encounter spores, but a gas mask is a good enough defence against it. That doesn't really make the threat as serious as it needs to be for a game like this, so it's transmitted through bites, too, and for some reason that I didn't pick up, the infected will bite you and tear you apart if they get to you. I don't really know why they would do that. I admit that perhaps I'm trying to rationalise it too much, but given that I knew a bit about cordyceps initially, and that I've recently spent the last few weeks working on a disease for a book that has required these kinds of thoughts, I can't help thinking that information is lacking in order to make the story more exciting.

   Either way, aside from all of my overthinking, I thought that the use of cordyceps was awesome, if also because it's a more viable threat than rising from the dead. Seriously, zombies, vampires, werewolves, they've all been done to death and I am sick of hearing about them. And because cordyceps only affects one species of animal - in this case, humans - nothing else is affected by it. Wildlife is still intact, and you only have to worry about other people.

Here's a snippet from BBC's Planet Earth, narrated by David Attenborough, about cordyceps (3 mins):