While looking at one of my lecture notes, I noticed a slide that the lecturer didn't elaborate much on. It was about toxoplasma gondii and there was an excerpt that said
"Suspicion is growing that one of the most common human parasites in the world is messing with our minds"

Sounds sinister?

Read about it! http://www2.nau.edu/~bah/BIO471/Reader/Sapolsky_2003.pdf
It's a really interesting article that is totally understandable in layman terms. SP1203. cough