Stomach-Turning Parasites

Single-celled microorganisms, tape worms, ticks and more can invade your body and use it as a host, but how do these unwelcome organisms get there? Find out. Plus, while most parasitic worms live in the human gastrointestinal tract, ophthalmologist Dr. Kerry Assil weighs in on a particular case where a worm was found inside a man's eyeball!