• Inflammation of the bronchioles characterized by swelling of the bronchioles and mucus accumulation. It is usually caused by the respiratory syncytial virus and affects children. Signs and symptoms include coughing, wheezing, and shortness of breath.
  NCI
  U.S. National Cancer Institute, 2021
• Bronchiolitis is an acute viral infection of the lower respiratory tract affecting infants < 24 months and is characterized by respiratory distress, wheezing, and/or crackles. Diagnosis is suspected by history, including presentation during a known epidemic; the primary cause, respiratory syncytial virus, can be identified with a rapid...
  Merck Manuals
  Merck & Co., Inc., 2025
• Bronchiolitis is an acute inflammatory injury of the bronchioles that is usually caused by a viral infection. Although it may occur in persons of any age, severe symptoms are usually only evident in young infants; the larger airways of older children and adults better accommodate mucosal edema.
  Medscape
  WebMD, 2025
• Bronchiolitis is a common lung infection in young children and infants. It causes inflammation and congestion in the small airways (bronchioles) of the lung. Bronchiolitis is almost always caused by a virus. Typically, the peak time for bronchiolitis is during the winter months.
  Mayo Clinic
  Mayo Foundation for Medical Education and Research, 2025
• Viral bronchiolitis is an acute viral infection of the lower respiratory tract. Although it can affect individuals of any age, the term is most often used to refer to infection in infancy. It is characterized by epithelial cell destruction, cellular edema, and airway obstruction by inflammatory debris and mucus. The clinical...
  Epocrates
  Athenahealth, Inc., 2019