My wife on mind-altering parasites:
There are dozens of similar behavior-altering parasites, each as fascinating as the next. Most of these parasites are specialized to a single species of host. The large majority infect insects or creatures on the low end of the evolutionary scale. There are some exceptions, including Toxoplasma gondii which lives in cats and infects humans. Toxoplasma gondii also infects rats and makes them lose their fear of cats- an infected rodent will waltz right up to cat’s hangout spot, only to be eaten and live inside the cat’s intestines long enough to get back to its preferred host, a human. Studies are still being done on the effects of Toxoplasmosis, but it seems to produce introverted and anti-social tendencies in the host, along immune and neurological problems.