Infection is spread by the fecal oral route.
Diagnosis is made by finding adult worms in stool or with vomiting and by microscopic stool exam. Eggs in stool are easily recognized microscopically with Lugol's iodine stain Eosinophilia is common with moderate to large infestations Intestinal obstruction occurs in children with large numbers of worms. Common bile duct obstruction and intestinal wall perforation can also occur. Initial infection is often asymptomatic. The interval between ingestion and the development of egg-laying adults is 8 weeks.