A child develops wheeze, dry cough, and transient pulmonary infiltrates with marked eosinophilia two weeks after soil ingestion. Larvae recovered from sputum show a distinctive morphology. This presentation results from which stage of Ascaris lumbricoides migrating through the lungs?

• A Fourth-stage larva returning to the intestine
• B Rhabditiform larva passed in faeces
• C Embryonated egg hatching in alveoli
• D Third-stage larva ✓

Explanation

Loeffler's syndrome in ascariasis occurs when third-stage larvae break out of pulmonary capillaries into alveoli during their obligatory heart-lung migration after ingestion of embryonated eggs. The resulting hypersensitivity reaction produces cough, wheeze, infiltrates, and eosinophilia. Eggs hatch in the intestine, not alveoli, and rhabditiform larvae are not produced by Ascaris, which passes fertilised eggs directly in faeces.

Reference: Paniker's Textbook of Medical Parasitology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.