In those individuals with preexistent lung disease and in those with the hyperinfection syndrome, including AIDS and other immunosuppressed patients, the migration of great numbers of larvae throughout the lungs produces extensive pneumonia and pulmonary edema and hemorrhage (Fig. 13.19). Pulmonary opacities are usually extensive in both lungs and are often associated with the development of ARDS, which can be fatal even after the parasites have been eradicated; in these patients irreversible pulmonary damage may have occurred as a result of toxic products from thousands of dead worms in the lungs. Some patients with advanced pulmonary strongyloidiasis may develop lung cavitation and abscess, usually from superimposed bacterial infection.

Pleural effusions can develop as a result of larval migration from the pulmonary parenchyma into the pleural cavity, and are seen more commonly in patients with severe strongyloidiasis associated with preexisting lung disease or the hyperinfection syndrome. Pleural fluid is usually seen in association with concomitant pulmonary opacities but can be the only radiographic abnormality in patients with pulmonary strongyloidiasis. Rarely, larvae may migrate from the pleura into the pericardium, causing pericarditis and pericardial effusion and an enlarged cardiac silhouette.

The prognosis in patients with pulmonary and/or intestinal strongyloidiasis depends on the severity of the disease. Most patients with autoinfection survive with proper treatment with thiabendazole or other appropriate antihelminthic drug. However, in those with the hyperinfection syndrome the mortality rate may exceed 70% despite appropriate therapy; subgroups with hyperinfection strongyloidiasis, such as HIV-positive or AIDS patients or those with secondary bacterial infection, may face a 90% or greater mortality.

Fig. 13.19 Overwhelming Strongyloides hyperinfection of the lungs in an immunosuppressed patient. The radiographic pattern is that of intense bilateral pulmonary edema. Pathologically there is inflammation and hemorrhage as well. Hyperinfection strongyloidiasis is one of many causes of widespread pulmonary disease to be considered in the immunosuppressed individual. (Courtesy of Dr. Eugene Klatte, Indianapolis, Indiana).