Paragonimiasis: a common cause of persistent pleural effusion in Lao PDR

Southeast Asia is the major endemic area for paragonimiasis. Diagnosis relies on identification of ova in the sputum, pleural fluid or tissue specimen, or serology. Low awareness, however, frequently results in the disease being overlooked. We report nine cases presenting as primary, massive and protracted pleural effusions. All patients had evidence of Paragonimus spp. in the pleural fluid; one discharged an adult worm through a chest tube during treatment with praziquantel. In three cases, resolution of symptoms and pleural effusions could not be achieved, despite repeated fluid evacuation procedures and courses of praziquantel, which contradicts the widely accepted statement of paragonimiasis being self-limited and easy to cure. The disease should be considered in any case of elusive pleural effusion occurring in endemic areas.