This isn't a parasite example but you might understand this example. When women are pregnant the baby basically tells the mother through her what they want to eat. Reason why women crave food items they didn't before. When I was pregnant I could not eat chicken or tolerate the smell of it. It would make me sick. Other then that, I love chicken and never had a problem with the smell of it. Just saying it is very possible for parasites to control any part of your body functions.