Holy Crap!

Science Daily: People with rage disorder twice as likely to have latent toxoplasmosis parasite infection - New study identifies link between Intermittent Explosive Disorder and exposure to the common toxoplasma gondii parasite typically found in undercooked meat, cat feces

summary - Individuals with a psychiatric disorder involving recurrent bouts of extreme, impulsive anger -- road rage, for example -- are more than twice as likely to have been exposed to a common parasite than healthy individuals with no psychiatric diagnosis. In a study involving 358 adult subjects, researchers found that toxoplasmosis, a relatively harmless parasitic infection carried by an estimated 30 percent of all humans, is associated with intermittent explosive disorder and increased aggression.