"How do people get Guinea worm disease?
People get infected when they drink standing water containing a tiny water flea that is infected with the even tinier larvae of the Guinea worm. Over the course of a year in the human body, the immature worms pierce the intestinal wall, grow to adulthood, and mate. The males die, and the females make their way through the body, maturing to a length of as much as 3 feet, and ending up near the surface of the skin, usually in the lower limbs. The worms cause swelling and painful, burning blisters. To soothe the burning, sufferers tend to go into the water, where the blisters burst, allowing the worm to emerge and release a new generation of millions of larvae. In the water, the larvae are swallowed by small water fleas, and the cycle begins again."