To the Editor: Parasitic infections of the respiratory tract are rare causes of haemoptysis in Western communities, and are often clinically indistinguishable from pulmonary tuberculosis.1

We report a case of a 19-year-old Burmese factory worker who presented to our outpatients department with a history of haemoptysis for 4 years. He was born in Myanmar (Burma) and lived in Malaysia for 2 years before migrating to Australia. He had no past history of significance, and denied having any contacts with tuberculosis. He was a non-smoker and was taking no regular medications.

His haemoptysis started in Myanmar, but increased in frequency after he migrated to Australia. He coughed up both fresh and old blood mixed with some sputum, and complained of weight loss of 6 kg, intermittent chest pain and headaches. He had no fever, night sweats, shortness of breath, dysuria, or gastrointestinal or neurological symptoms. He appeared well, and findings of a general physical examination were unremarkable.

Chest x-rays from before this presentation, which included migrant screening x-rays, were normal, but his most recent chest x-ray revealed a round lesion posteriorly. A computed tomography scan organised by the patient’s general practitioner showed an area of consolidation at the base of his left lung, not typical of tuberculosis which was the primary suspect in this case.

Blood tests showed a raised white cell count of 14. 5 × 109/L (reference range [RR], 4.0–11.0 × 109/L) with a neutrophil count of 11.33  × 109/L (RR, 2.0–7.5 × 109/L) and an eosinophil count of 0.51 × 109/L (RR, 0.04–0.4  × 109/L), an erythrocyte sedimentation rate of 44 mm/h (RR, 1–10 mm/h) and C-reactive protein level of 20 mg/mL (RR, < 5 mg/mL). The result of a QuantiFERON-TB Gold test for tuberculosis was negative.

Attempts to obtain sputum samples were unsuccessful, and the patient underwent a bronchoscopy that revealed white milky mucous secretions within the lower lobe of the left lung, where a bronchial lavage was performed. Microscopy of bronchial washings revealed the presence of parasitic structures consistent with Paragonimus westermani (Box 1).

Therapy with praziquantel was initiated at a dose of 1200 mg orally, twice daily for 2 days. His condition improved quickly and, on review in the outpatients department 4 weeks later, he had no clinically or radiologically evident recurrence of infection.

Paragonimiasis is a common endemic infection in South-East and East Asia, particularly in India, China, Japan and the Philippines. Humans acquire the infection by eating raw or undercooked crayfish and freshwater crab, in which the metacercariae encyst. Once the organisms reach the duodenum, they excyst, penetrate the gut wall, and travel through the peritoneal cavity as immature flukes. They then migrate through the diaphragm and pleural space to reach the lungs, where they form adult worms.2

Early after infection, pleuritic chest pain may develop, in some cases accompanied by a pneumothorax or pleural effusion. Later, with invasion of the lung parenchyma, low-grade fever, cough or streaky haemoptysis may develop. Once the adult worms inhabit the lungs, usually after 2 months, recurrent haemoptysis becomes the cardinal symptom.3

Pulmonary paragonimiasis is most commonly misdiagnosed as tuberculosis, owing to many similarities in the clinical pictures of the two infections (Box 2).4,5 In a patient from a known endemic area, differential diagnoses should be considered and every effort should be made to obtain sputum samples or bronchial washings to distinguish between these two conditions. Serological tests are available if sputum or washings cannot be obtained.

1 Paragonimus westermani eggs detected on microscopy of bronchial washings