What is the differential diagnosis between bronchiolitis and reactive airway disease (RAD) in a 7-month-old infant?

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Last updated: May 16, 2025 • View editorial policy

Differential Diagnosis for Bronchiolitis vs Reactive Airway Disease in a 7-Month-Old

Single Most Likely Diagnosis

  • Bronchiolitis: This is the most likely diagnosis in a 7-month-old presenting with respiratory symptoms, as bronchiolitis is a common lower respiratory tract infection in infants, typically caused by the respiratory syncytial virus (RSV).

Other Likely Diagnoses

  • Reactive Airway Disease (RAD): Also known as asthma, RAD is a condition characterized by episodic airway obstruction, which could be a consideration in this age group, especially if there's a history of similar episodes or atopic conditions.
  • Viral Pneumonia: Other viral pathogens can cause pneumonia in infants, which might present similarly to bronchiolitis, making it an important differential diagnosis.

Do Not Miss Diagnoses

  • Congenital Heart Disease: Although less common, undiagnosed congenital heart disease can present with respiratory symptoms due to pulmonary congestion or other complications, making it crucial not to miss.
  • Foreign Body Aspiration: This is an emergency that can cause sudden onset of respiratory symptoms and must be considered, especially if the history suggests a possible aspiration event.
  • Pertussis (Whooping Cough): Given the potential for severe disease in infants and the fact that vaccination may not be fully effective at this age, pertussis is a critical diagnosis not to miss.

Rare Diagnoses

  • Cystic Fibrosis: While rare, cystic fibrosis can present with recurrent respiratory infections and should be considered in infants with persistent or severe respiratory symptoms.
  • Primary Ciliary Dyskinesia: A rare genetic disorder affecting the motility of cilia, leading to recurrent respiratory infections, which could be a consideration in infants with persistent symptoms.
  • Immunodeficiency: Certain immunodeficiencies can increase the susceptibility to severe or recurrent infections, making this a rare but important differential diagnosis in infants with unusual or severe presentations of common infections.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.