Toxoplasma gondii – 30 to 50% of humanity has a brain parasite

My (almost) entirely unscientific thesis is that this is why cats are domesticated. They are neurotic and totally useless pets, but people love them, specifically certain people. The "crazy cat lady" probably just had toxo induced psychosis. [1] PS. The immunosuppressant drug that treats toxo symptoms in the immunocompromised (ie. AIDs infected) is the one that Martin Shkreli got famous raising the price of. [1]: http://www.theatlantic.com/magazine/archive/2012/03/how-your...