Stop Exogenous Allergic Alveolitis (EAA) in Childhood

Inclusion Criteria: 1. Newly or previously diagnosed but not appropriately treated EAA in children, adolescents and young adults, aged between 3 and 25 years. The diagnosis of EAA must be confirmed by independent review of the findings by an expert panel and must be based on the presence of at least 4 of the following findings: * History of appropriate allergen exposure * Restrictive lung function (FVC \< 80% predicted for age and FVC/FEV1 \< 1) testing, if appropriate for age (usually \> 5 y) * Positive serum precipitins for bird/fungus exposed to (other allergens have rarely, if every been demonstrated in children) * Lymphocytosis in BAL (\> 20% of cells are lymphocytes) * HRCT showing the characteristic nodular, linear or reticular opacities, and ground glass pattern with increased attenuation. * Lung biopsy demonstrating lymphocytic alveolitis, bronchiolitis, and non-caseating histiocytic granulomatas. * Controlled allergen exposure followed by characteristic reaction, including fever, coughing, restriction on lung function, hypoxemia/desaturation at rest or with exercise 2. Unchanged inhaled steroids if on; if off, no plans to introduce them in the following 6 months 3. Agreement to home visit by independent study physician Exclusion Criteria: 1. Contraindication for usage systemic steroids 2. Critically ill patients needing respiratory support 3. Non-compliance with medical treatments and interventions 4. Women with childbearing potential and not practicing a medically accepted contraception during the trial and a positive pregnancy test (serum or urine) before and at the end of the trial. Reliable contraception are systematic contraceptives (oral, implant, injection) and diaphragm or condoms with spermicide. 5. Pregnancy and lactation. 6. Participation in another trial for EAA during the last 4 weeks or not beyond the time of 4 half-lives of the medication used. In the unlikely event a subject is already in another clinical study but not for EAA, that study must be stopped and the subject may be treated according to this protocol; a latency time between the two studies does not appear reasonable, as acute intervention is necessary for EAA. Treatment may be best done in the frame work of this protocol.