The freeliving males and females mate, produce more larvas, and some of these larvas will develop into freeliving larvas, while other will develop into parasitic larvas. This freeliving life cycle is the reservoir for human infections.

The parasitic larvas infect the human host by penetrating the skin. They migrate to the lungs via the circulatory system and penetrate the alveoli in the small bronchioles. They are coughed up and swallowed. The larvas mature into parasitic females in the small intestine.