Paragonimiasis Following Ingestion of Frozen Freshwater Crab: Two Case Reports

Paragonimiasis is a zoonotic disease caused by trematodes belonging to the genus Paragonimus. It is acquired by ingesting freshwater crustaceans or raw game meat. Here, we report two patients (a couple) who developed paragonimiasis and pulmonary lesions with peripheral eosinophilia after sharing and consuming previously frozen freshwater crabs (Eriocheir japonica) together at the same restaurant in Tokyo. One patient developed peripheral airspace consolidation, which was initially misdiagnosed as chronic eosinophilic pneumonia, whereas the other exhibited eosinophilic pleural effusion. Antiparasitic antibody testing of serum using enzyme-linked immunosorbent assay (ELISA) established a diagnosis of paragonimiasis. Both cases were effectively treated with praziquantel. These cases demonstrate that frozen freshwater crabs remain a potential source of paragonimiasis, underscoring the critical role of dietary history in patients with eosinophilic lung diseases.