From the Guidelines
Croup is primarily caused by viral infections, with parainfluenza viruses being a common cause, as evidenced by the significant healthcare burden associated with parainfluenza virus-related hospitalizations 1. The most common viral causes of croup include:
- Parainfluenza viruses (types 1,2, and 3)
- Respiratory syncytial virus (RSV)
- Influenza viruses
- Adenoviruses
- Rhinoviruses These viruses infect the upper airway, causing inflammation and swelling of the vocal cords, trachea, and bronchi, which leads to the characteristic symptoms of croup, such as a barking cough, stridor, and respiratory distress 1. Croup typically affects children between 6 months and 3 years of age, with peak incidence in the second year of life, and is more common during fall and winter months when respiratory viruses circulate more widely. In rare cases, croup can be caused by bacterial infections, allergic reactions, or inhalation of irritants, but viral infections are the primary cause, and reducing hospitalizations for croup, such as those caused by parainfluenza virus, can lead to significant healthcare savings and improved value-based care delivery 1.
From the Research
Causes of Croup
- Croup is often caused by viruses, with parainfluenza virus (types 1 to 3) as the most common cause 2, 3, 4, 5, 6
- Parainfluenza virus accounts for the majority of cases, approximately 75% of infections 2
- Other causes, including bacterial tracheitis, epiglottitis, foreign body aspiration, peritonsillar abscess, retropharyngeal abscess, and angioedema, should be considered in the differential diagnosis 3, 5
- RSV is also a common pathogen causing croup 6
Demographics
- Croup affects about 3% of children per year, usually between the ages of 6 months and 3 years 2
- The disease is characterized by varying degrees of inspiratory stridor, barking cough, and hoarseness because of laryngeal and/or tracheal obstruction 4
Clinical Presentation
- Croup symptoms usually start like an upper respiratory tract infection, with low-grade fever and coryza followed by a barking cough and various degrees of respiratory distress 3
- The symptoms usually resolve within 48 hours, but severe upper airway obstruction can, rarely, lead to respiratory failure and arrest 2