Parasitic diseases of the respiratory tract

The human pulmonary system can be affected by a variety of parasites. This review focuses on the most common parasitic infestations involving the lung, except for protozoon disease.

In many parasitic lung conditions, the clinical manifestations and the imaging findings are non-specific and can make diagnosis challenging. Hydatid disease and paragonimiasis involve the lung directly. Chronic schistosomiasis can lead to pulmonary hypertension. Strongyloides stercoralis infestation is capable of transforming into a fulminant fatal disease. In many types of nematode infestations, the pulmonary phase can cause acute eosinophilic pneumonia. Chest radiographs of patients with paragonimiasis and dirofilariasis can cause diagnostic confusion. Cases of tropical pulmonary eosinophilia typically present with refractory bronchial asthma. Most of these diseases are initially diagnosed by detecting eggs or larvae in stool, sputum, pleural fluid or tissue, and are confirmed by serologic testing. Cystic hydatid disease generally requires surgical treatment, whereas almost all other parasitic lung conditions can be treated medically.

Although most parasites that affect the lung are endemic to tropical and subtropical regions, immigration and travel practices have resulted in transfer of these diseases to other areas. It is important for physicians to know the epidemiologic characteristics, clinical presentations, and treatments of choice for these conditions.