Distinguish intestinal ascariasis from tissue migrans causing Loeffler syndrome; name the underlying process.

• A. Intestinal ascariasis involves adult worms in the gut; Loeffler syndrome due to larval migration through lungs with eosinophilia
• B. Both involve adult worms in the gut
• C. Loeffler syndrome involves intestinal obstruction
• D. Ascariasis is caused by bacterial infection

Answer: (B)

Two distinct stages define Ascaris infections. In intestinal ascariasis, adult worms live in the lumen of the small intestine and cause gastrointestinal issues, sometimes leading to obstruction with heavy loads. Loeffler syndrome, on the other hand, results from migrating larvae moving through tissues, especially the lungs, where their passage triggers an eosinophil-rich inflammatory reaction and transient pulmonary symptoms.

The underlying process is larval migration through tissues during the parasite’s life cycle—larvae travel from the gut to the lungs, cause tissue reaction and eosinophilia during their pulmonary passage, and are then coughed up and swallowed back into the gut to mature. This contrasts with intestinal ascariasis, where the disease is due to adult worms inhabiting the gut rather than migrating through tissues.

Therefore, the statement that best captures the distinction notes adult worms in the gut for intestinal disease and larval pulmonary migration with eosinophilia for Loeffler syndrome. The idea that both conditions involve only adult worms in the gut, or that Loeffler syndrome is about intestinal obstruction, or that ascariasis is bacterial, does not fit the actual life cycle and pathophysiology.