Loveable, stealthy and prone to excessive napping, your cat is also a highway for one of the most common internal parasites in the world: Toxoplasma gondii. Unless you raised your pet from a kitten within an impregnable fortress, there's a good chance it picked up the pesky parasite at some point in its life.

This particular microscopic protozoan lives in a number of rodents, birds and other small animals. When your cat eats these creatures, it carries out a vital role as the primary host in the parasite's life cycle. You see, the rodents and birds were only a temporary stop along the way; they're merely intermediate hosts. But your cat is the main station because its gut is the only place these parasites can reproduce!

The Toxoplasma multiply in the lining of an infected cat's intestines and, for two or three weeks following infection, millions of microscopic Toxoplasma young, called oocysts, ship out aboard cat feces. Any creature that encounters the stowaway-laden waste is susceptible to accidental infection. This means touching a litter box, infected soil, infected water or even infected garden veggies. Where there's a poop, there's a way.

The U.S. Centers for Disease Control and Prevention estimates that 22.5 percent of the United States' 12-and-older population currently carries the parasite -- and estimates run as high as 95 percent in some parts of the world. Experts have long thought that only unborn infants and immune-weakened individuals were at risk of developing symptoms. In recent years, however, studies have highlighted many possible neurological effects of Toxoplasma.

Now lock the cat away and hold onto your brain, because we're about to look at five ways these poop-based parasites might reprogram your mind to self-destruct.