Adults are in lumen of small intestine, deposit eggs in feces. Eggs hatch in newly infected host, larvae move from small intestine, into liver, then heart, lungs, up bronchii, swallowed, then back to small intestine.
Adult worms usually do not cause acute symptoms. However, some may cause stunted growth. High worm concentrations may cause abdominal pain and intestinal obstruction. During the lung phase of larval migrartion, pulmonary symptoms may occur; cough, dyspnea..