Everybody knows the usual relationship between cats and mice. Cats chase and kill mice, so naturally, mice are terrified of cats. However, an observation of the parasite known as Toxoplasma gondii causes mice to no longer fear cats while infected. Toxoplasma gondii is parasite that can only reproduce in the intestines of cats and is very harmful to women who are pregnant. It can cause blindness or even death for the fetus.The parasite apparently alters the brain of the mouse causing it to lose it’s innate fear of cats. This seems all too convenient seeing as how, mentioned above, that this parasite can only be reproduced inside of a cat. The fact that the mice no longer fear cats makes it easier for the cats to catch and kill the mice, making it easier for the parasite to reproduce. It was recently discovered that after the parasite is no longer found inside the mice it appears that their fear of cats is gone permanently. I first learned of this infection in my Zoology class during my senior year which made me fear my cats a little bit because this does not sound like it would be a fun parasite to have (not that any seem fun to have…). This discovery is actually incredibly fascinating because it shows how this parasite has ways of altering the brain of a mammal. Who’s to say that it can’t eventually do the same to us?