A Rare Pediatric Case of Severe Bird Fancier's Hypersensitivity Pneumonitis Presented with Viral Pneumonitis-Like Picture

Bird Fancier’s Syndrome is a rare, non-atopic immunologic response to repeated or intense inhalation of avian (bird) proteins/antigens found in the feathers or droppings of many species of birds, which leads to an immune mediated inflammatory reaction in the respiratory system. Although this is the most common type of hypersensitivity pneumonitis reported in adults, it is one of the classification of a rare subtype of interstitial lung disease that occurs in the pediatric age group of which few case reports are available in the literature. The pathophysiology of hypersensitivity pneumonitis is complex; numerous organic and inorganic antigens can cause immune dysregulation, leading to an immune related antigen-antibody response (immunoglobulin G–IgG- against the offending antigen). Diagnosing Bird Fancier’s disease in the pediatric age group is challenging, history of exposure is usually missed by health care providers, symptoms and clinical findings in such cases are nonspecific and often misdiagnosed during the acute illness with other common diseases such asthma, or acute viral lower respiratory tract infection, and the lack of standardization of criteria for diagnosing such condition, or sensitive radiological or laboratory test. Treatment, on the other hand, is also controversial. Avoidance of the offending antigen could be the sole or most important part of treatment, particularly in acute mild and moderate cases. Untreated cases can result in irreversible lung fibrosis. In this case report, we highlight how children presenting with an acute viral lower respiratory tract infection can overlap with hypersensitivity pneumonitis. Early intervention with pulse steroids markedly improves the patient’s clinical course.