They go from the liver to the heart and then to the lungs by way of the blood stream. In the lungs they molt to the fourth-stage in 5 or 6 days. The nematodes main food is liquid contents of the intestinal lumen. Egg laying begins 50 to 60 days after the eggs are ingested. If large numbers of juveniles are present in the lungs they may cause pneumonia.
Juveniles entering the liver or other organs induce inflammatory reactions.
If large numbers of migrating juveniles are present they may cause serious symptoms, especially if present in the brain. A few adults in the intestine cause no serious symptoms. Larger numbers compete with the host for food and may cause intestinal discomfort, nausea, vomiting and diarrhea. In children the worms may cause poor growth, loss of weight and abdominal symptoms. Rarely the adult worms rupture the intestinal tract and enter the peritoneal cavity causing peritonitis and may obstruct the bile ducts.