There are already breeds of parasitic larvae that invade certain insects and cause them to do strange things. I don't have time to google it, but specifically there is a wasp larvae that is implanted into a certain type of snail I think it is that causes the snail to go nuts, climb to the top of a plant, only to get eaten which releases the larvae from inside the bird, who then poops it out and it develops into a new wasp.
I also think I read about a fungus that some ants get that does the same thing. Takes over their brains, causes them to act strange, and then crawl to the tops of leaves where they become easy prey and then the spores spread in birth/animal poop.
I ALSO read an article that claimed that we have only discovered an estimated 20-25% of the species of animals on earth, and less than that of flora...so to think a certain "substance" or "life form" doesn't exist out there that can totally turn our worlds into a Michael Jackson video isn't out of the question.
Its reason # 234 why I like 30 rounders. Ill either be well defended, or an impressively armed zombie...like in the games Ill be a boss zombie that has epic drops.