The aymptoms are nonspecific and usually progress subacutely or chronically with clinical symptoms similar to those of community-acquired pneumonia, which often delays the diagnosis and treatment. The use of antibiotic therapy for the empirical treatment of infection is ineffective, although macrolides are used in the treatment of patients with mild symptoms or as an adjuvant therapy, given their immunomodulatory properties. The disease usually develops after a prodrome, wherein the patient shows flu-like symptoms, including fever, fatique, dry cough and dyspnea. Typically, the diagnosis is not suspected in the first 4 to 10 week. The physical examination is nonspecific, and inspiratory crackles occur in two thirds of cases and more commonly in secondary OP.