Occupational exposure to freshwater crustaceans as a route of paragonimiasis presenting with eosinophilic pleural effusion misdiagnosed as tuberculous pleurisy: A case report and literature review

Paragonimiasis, a foodborne parasitic disease caused by Paragonimus, typically presents with pleural effusion and is often misdiagnosed as tuberculous pleurisy, especially in endemic regions. The present study aimed to investigate the causes of misdiagnosis of pleural effusion (PE) caused by paragonimiasis as tuberculous pleurisy and to propose preventive strategies. The clinical diagnostic and treatment course of one patient with paragonimiasis misdiagnosed as tuberculous PE (TPE) was analyzed. A literature review of English‑language case reports and series on paragonimiasis with PE misdiagnosed as TPE was performed using PubMed, Google Scholar, and Web of Science databases up to January 1, 2026. A 41‑year‑old male patient presented to Gucheng County People's Hospital (Shiyan, China) in October 2024 with a 10‑day history of cough, sputum production, fever and shortness of breath. with cough, sputum, fever and dyspnea. Chest computed tomography (CT) showed left‑sided PE. Tuberculosis antibody detection was positive and erythrocyte sedimentation rate was elevated. The patient was misdiagnosed with TPE and showed poor response to antituberculosis treatment. At 8 months later, readmission revealed markedly elevated eosinophils in peripheral blood (18%; normal range: 0.4‑8.0%, absolute count, 2.61x10⁹/l; normal range: 0.02‑0.5x109/l), pleural fluid and pleural biopsy tissue. The patient had longterm occupational exposure to freshwater aquatic products without a history of raw seafood ingestion. Intradermal test for Paragonimus‑specific antigen (IDTPA) and serum Paragonimus IgG antibody were both positive. Following four courses of praziquantel (25 mg/kg three times daily; 3 days/course), the patient achieved clinical cure with resolution of PE and normalization of eosinophil count (0.46x10⁹/l). The correct diagnosis of paragonimiasis was established by peripheral and pleural eosinophilia, positive IDTPA and serology and response to praziquantel. A literature review of 16 English language publications (51 cases) showed that 92.2% of patients had a history of raw or undercooked freshwater product ingestion, 94.1% had peripheral blood eosinophilia and 93.8% were seropositive by ELISA. By contrast, the present case involved long‑term occupational exposure to freshwater aquatic products without raw seafood ingestion, an unusual but important route of infection. All reported patients responded to praziquantel. Elevated eosinophil levels in peripheral blood and pleural fluid and biopsy tissue are valuable clues for the diagnosis of paragonimiasis. Detailed inquiry into occupational and environmental exposure in addition to dietary history is essential. IDTPA and/or serum Paragonimus IgG antibody testing enables early diagnosis. Praziquantel remains the standard effective treatment.