To investigate the clinical features and practical diagnostic method of lung fluke disease (LFD) that presented with pleural effusion as the main clinical manifestation.

The clinical diagnosis and treatment of a 49-year-old male patient with LFD who complained of intermittent dull pain and dyspnea in bilateral lower chest for one year with radiological findings of left pleural effusion and admitted to Taihe Hospital of Shiyan City, and the causes of misdiagnosis were analyzed.

This LFD patient with pleural effusion was misdiagnosed as tuberculous pleural effusion for longer than one year. There was abnormal elevation of eosinophils in pleural tissue, and the absolute count of eosinophils in peripheral blood was as high as 2.64 × 10⁹/L. Finally, combined with the positive results of intradermal tests for Paragonimus-specific antigens (IDTPA) and enzyme-linked immunosorbent assay (ELISA) of serum antibodies to Paragonimus, the diagnosis of lung fluke disease was confirmed. The patient received praziquantel (25 mg·kg^-1· times^-1, 3 times a day) for 4 courses outside the hospital according to the doctor’s advice, and demonstrated clinical improvement.

Elevated eosinophils in peripheral blood and pleural biopsies are important for the diagnosis and therapeutic effect analysis of LFD. Detailed inquiry of personal history and timely IDTPA are the keys to early diagnosis of LFD.