Mind-controlling parasites are some of the scariest creatures around

Scott Sutherland
October 31, 2013

Are you looking for something scary for Halloween, but the usual vampires, werewolves and other mythical beasts just aren't doing it for you this year? There are some real-world monsters out there that are much scarier than anything we can cook up in a story — secretly invading our bodies, feeding on us, and they can even control our minds. I'm talking about parasites.

Take Ophiocordyceps unilateralis, a fungus that's found in tropical rain forests around the world. Anyone who's played the video game The Last of Us is familiar with this one, because it's the cause of the 'zombie' apocalypse in the game's fictional back-story. The effects of this fungal parasite are very real, though, as it infects ants, takes over their central-nervous system to make them crawl up onto plant leaves hanging above the ant colony, where the ant bites down on a leaf vein in a death-grip and then dies. The fungus grows stalks out of the ants body, which produce spores to rain down on the colony to infect more ants. It was a mutant form of this type of fungus that brought the world down in the game, but the designers really did their homework.

Another scary one is Toxoplasma gondii, for it's ability to steal away the self-preserving fear of predators. This single-celled organism infects rats with the 'single-minded' goal of putting its host into the belly of the nearest cat. To do this, it sabotages the parts of the rat's brain that specifically deal with its fear of cats, and just to make this a sure thing, it even goes so far as to make the rat sexually attracted to cat odours. The unfortunate end result of this (at least for the rat) puts the parasite exactly where it wants to be, because it can only reproduce inside cats. Even scarier... T. gondii can, and does, infect any warm blooded animal, including us. We may not be on the menu for cats, but who knows what T. gondii is actually doing to the people infected?

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Our bodies play host to a multitude of bacteria and other microorganisms, but it's disturbing to know that some of these things are capable of hijacking us, often without us realizing that there's anything wrong until it's often too late.

The two I've talked about here aren't the only ones, either. CBC's The Nature of Things is airing an episode tonight, specifically about these kinds of parasites and the effects that they have. If you're trapped inside on this rainy, blustery Halloween night, check it out.

(Photo courtesy: The National Science Foundation)

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