In Ascaris lumbricoides infection, which phase is associated with pulmonary symptoms due to larval migration?

• A. Adult worms in the intestine
• B. Eggs in stool
• C. Larval migration through the liver without lung involvement
• D. Larval migration through the lungs causing cough and infiltrates

Answer: (D)

The key idea is that Ascaris undergoes a larval migratory phase that passes through the lungs before settling in the intestine. During this pulmonary segment, the larvae trigger cough, wheezing, and transient infiltrates—classic of Löffler’s syndrome with eosinophilic response. After migrating through the lungs, the larvae are swallowed and mature into adults in the small intestine, where they cause intestinal symptoms and eggs appear in the stool. So the pulmonary symptoms arise specifically from the larval migration through the lungs, not from adult worms in the intestine or from eggs in stool.