Another New Scientist gallery, this time: parasites! I especially like the first picture, of a hookworm. The hookworm, Necator americanus, is a type of roundworm that infect the small intestines of mammals (like, unfortunately, humans) through contaminated food and drink. The hookworm - the little bastard - feed by attaching itself to the intestinal wall of the host with it's cutting plates and voraciously sucking the host's blood. This can cause a nasty blood disease called anemia which, altough rarley fatal, can stunt the intelectual growth of susceptible children. It's very pretty, though.
(Note: hookworm infection does not cause vampirism!)