Which food-borne trematode is linked to ingestion of undercooked crustaceans and can cause pulmonary symptoms when larvae migrate to the lungs?

• A. Clonorchis sinensis
• B. Paragonimus westermani
• C. Fasciola hepatica
• D. Opisthorchis viverrini

Answer: (B)

Paragonimus westermani is a lung-dwelling fluke acquired by eating undercooked freshwater crustaceans such as crabs or crayfish. After the metacercariae are ingested, they excyst in the duodenum and migrate through the peritoneal cavity and diaphragm to the lungs, where they mature and produce symptoms. The pulmonary involvement leads to chronic cough, chest pain, and sometimes hemoptysis, reflecting the parasites’ migration and inflammation in lung tissue. Diagnostic clues include finding eggs in sputum or stool and characteristic imaging or serology findings; treatment typically involves antiparasitic therapy such as praziquantel.

The other trematodes listed cause different disease patterns: liver flukes like Clonorchis sinensis and Opisthorchis viverrini are acquired from undercooked fish and mainly affect the biliary tree, causing cholangitis or biliary obstruction; Fasciola hepatica migrates to the liver after ingestion of aquatic vegetation and presents with hepatic symptoms rather than pulmonary ones.