Parainfluenza Virus (Croup)

Summary

The parainfluenza virus is a paramyxovirus that causes croup. Croup generally presents with a barking seal-like cough. Severe upper airway obstruction in croup can also cause pulsus paradoxus. Finally, patients with croup have a characteristic steeple sign on their x-ray scans, which is indicative of a narrowing in the upper respiratory tract.

Key Points

• Parainfluenza virus
  • Transmission
    • Respiratory droplets or fomite exposure
  • Presentation
    • Croup (acute laryngotracheobronchitis)
      • barking “seal-like” cough and inspiratory stridor
      • Severe croup can lead to pulsus paradoxus secondary to upper airway obstruction
    • Narrowing of upper trachea and subglottis leads to characteristic steeple sign on X-ray
  • Treatment
    • Supportive care; no antivirals indicated