<unk>  is the most common lower respiratory tract infection in pediatric patients between 1 month and 2 years of age.  It is usually caused by the respiratory syncytial virus (RSV) and is characterized by inflammation, edema, and necrosis of the bronchiole's epithelium. It is classified according to histological features as<unk>  obliterans, proliferative<unk> , diffuse panbronchiolitis, or respiratory<unk> . The<unk>  severity score is used to classify<unk>  into 4 classes. Typical clinical manifestations include rhinitis, cough, wheezing, respiratory rales (crackles), use of respiratory accessory muscles, and/or nasal flaring. In adults, common risk factors in the development of<unk>  include exposure to cigarette smoke, living in crowded areas, and being immunocompromised. In infants, the risk factors include age < 6 months, lack of breastfeeding, prematurity, and having congenital heart diseases. The mainstay of treatment of<unk>  is supportive therapy.
Bronchiolitis
Bronchitis
Croup
Mediastinitis
Tracheitis
Alveolitis
Bronchiectasis
Lung abscess