I grew up in Florida, and on one occasion went barefoot in some black, muddy soil. I still experience redness, dry skin, and severe itching on the bottoms of my feet, especially in the arch area. I never go barefoot and did not either before or after that incident. Hookworm infections used to be common in the southern U.S., where warm weather combined with poor sanitation and the habit of going barefoot allowed them to spread. These infections are still very common in the developing world, and there are estimates that up to 25 percent of the world's population has been infected.
Hookworms live in the intestine of infected humans.
They attach themselves to the lining of the intestine and live off the host's blood. In very severe infections, they can produce anemia and malnutrition if the iron and nutrients in the blood loss are not adequately replaced. Many people, though, have light infections and are never aware of the worms. The worms reproduce in the intestine and lay eggs, which pass out of the body in the stool. Where sanitation is poor, the stool containing the eggs is often mixed in with dirt or mud.