Parasitic pneumonia.

With few exceptions, the parasitic pneumonias most commonly encountered in the Western Hemisphere are diseases of compromised hosts; patients with AIDS are at particular risk. Pneumocystis carinii pneumonia occurs eventually in 80% of AIDS patients; bronchoalveolar lavage is quite sensitive in establishing this diagnosis. Toxoplasma gondii pneumonia, seen most often in the patient with AIDS, is characterized by multisystem involvement. Strongyloides stercoralis infection is endemic in the Southeastern United States. Pulmonary strongyloidiasis is seen in patients receiving glucocorticoids or chemotherapy, and in patients with AIDS or other causes of T cell dysfunction. Larvae may be seen on Gram's stains or wet mounts of sputum. Ascaris and hookworm infections may present with pulmonary infiltrates and eosinophilia during the larval migration phase. Dirofilaria, Paragonimus, and Entamoeba histolytica involvement of the lung are less common and require a good epidemiologic history and clinical suspicion for diagnosis.