
The ramifications are spooky. Check out the links within the article too for some other nasty parasites that control their host.
This served to remind me of Night of the Creeps, an 80s zombie flick with a twist: brain slugs. They get in your mouth, and you're a goner. They even resurrect you if you are dead. If you can, try to get the version of the film with the alternate director's ending. Golden stuff.

I replied, in a moment of bad-movie clairvoyance, "I could [expletive deleted] a better movie."
Kit: "Really?"
Later Kit confirmed my suspicions. I myself unfortunately did end up seeing a large portion of Van Helsing as well, when my drunken room mates rented it. And I was right. I'm telling you now, it doesn't matter that one of the big guys from the Dawn of the Dead remake was involved; it doesn't even matter that it looks like a zombie movie (in the sense that people become flesh-eating, brainless monsters). It's going to be bad. Believe me when I say that. And not bad in a good, Night of the Creeps way. No, bad in Van Helsing way. You've been warned.