Paragonimus westermani

Background

• Also known as the oriental lung fluke
• Most common species of Paragonimus that infects humans

Epidemiology

• Distributed within southeast Asia and east Asia, including China, Korea, Japan, the Philippines, Taiwan, and India
  • Other species are endemic to other parts of the world, including Paragonimus kellicotti in North America
• Primarily transmitted by consumption of raw or undercooked crab or crayfish
• Lifespan of a lung fluke is up to 20 years (if untreated)

Clinical Manifestations

Pulmonary Paragonimiasis

• Acute phase: diarrhea, abdominal pain, fever, cough, urticaria, hepatosplenomegaly, pulmonary abnormalities, and eosinophilia
  • As larvae penetrate the diaphragm, patients can have pleuritic chest pain and develop pneumothorax or pleural effusion (usual exudative and eosinophilic)
• Chronic phase: cough, sputum production, and hemoptysis
  • May last for years

Extrapulmonary Paragonimiasis

• Immature flukes can migrate into brain, abdomen (including intestinal wall, liver, spleen, pancreas, kidney, adrenal gland, peritoneal cavity, ovary, mesenteric lymph nodes), and subcutaneous tissues
  • Also, more rarely, to heart, mediastinum, muscle, spinal sord, parotid gland, testes, and breasts
• Eggs can deposite into ectopic sites as well, causing cyst, abscess, or granuloma formation

Management

• First-line: praziquantel 75 mg/kg/day in three divided doses, for three days
• Second-line: triclabendazole 10 mg/kg p.o. once or twice1