1. Eggs are passed in the stool.
2. If the eggs are deposited in a warm, moist place on loose soil, larvae hatch in 1 to 2 days.
3. After 5 to 10 days, the larvae become infective.
4. When they come in contact with the human host, they penetrate the skin and are carried through the blood vessels to the heart and then to the lungs. Secretions from the lungs, which contain the larvae, are coughed up and swallowed, passing into the stomach.
5. The larvae reach the small intestine, where they mature into adults. Adult worms live in the small intestine. They attach to the intestinal wall, feed on blood, and produce eggs.
Image from the Centers for Disease Control and Prevention, Global Health, Division of Parasitic Diseases and Malaria.