Löffler Syndrome

Parasitic infections, such as ascariasis, ancylostomiasis, and strongyloidosis are the most common cause, but an identifiable etiologic agent may not be found in up to one-third of patients.

The diagnosis of Löffler syndrome is based on characteristic and often transient respiratory symptoms that include a nonproductive cough, wheezing, and sometimes systemic symptoms such as fever. Chest radiograph, when repeated, may show migratory oval opacities, reflecting the migratory nature of the larvae. Peripheral blood eosinophilia (eosinophil counts > 500 cells/mcL [0.5 × 10⁹/L]) may be present. Rarely, transient hemoptysis is reported.

As with other eosinophilic pulmonary disorders, diagnosis requires the exclusion of other types of eosinophilic lung disease. For example, acute eosinophilic pneumonia is a distinct entity with acute onset, severe hypoxemia, and typically a lack of increased blood eosinophils at the onset of disease; chronic eosinophilic pneumonia is characterized by recurrent episodes of more severe respiratory symptoms and frequently increased peripheral blood eosinophils.

The disease usually resolves within 1 month.

Treatment of Löffler syndrome is symptomatic and may consist of glucocorticoids (1). If a parasitic infection is identified, appropriate antiparasitic therapy should be initiated.