Croup is a viral infection causing inflammation and swelling of the upper airway (larynx, trachea), characterized by a harsh, barking cough, hoarseness, and inspiratory stridor. It primarily affects children aged 6 months to 3 years, with about 15% experiencing at least one episode by age six.
Bronchiolitis affects the lower respiratory tract, specifically the bronchioles, leading to inflammation, swelling, and mucus buildup. It mainly impacts infants under two years old, with RSV (respiratory syncytial virus) responsible for approximately 70% of cases.
Both illnesses are highly contagious, spreading via respiratory droplets and close contact.
The typical duration of croup symptoms is 3 to 7 days, often worsening at night, while bronchiolitis symptoms last 1 to 2 weeks with gradual improvement.
Diagnosis is primarily clinical but may include neck X-rays (croup) showing the “steeple sign” and pulse oximetry to monitor oxygen levels.
What is Croup?
Croup is a viral infection causing inflammation and swelling of the upper airway (larynx, trachea), characterized by a harsh, barking cough, hoarseness, and inspiratory stridor. It primarily affects children aged 6 months to 3 years, with about 15% of children experiencing at least one episode by age six (Rosen et al., 2021).
Each year, croup accounts for approximately 3% of pediatric emergency visits in the U.S. (Hall et al., 2004), and about 5% of cases require hospitalization due to breathing difficulties. The illness peaks in fall and early winter, coinciding with parainfluenza virus season—the leading cause of croup (Heikkinen & Järvinen, 2003).
What is Bronchiolitis?
Bronchiolitis affects the lower respiratory tract, specifically the bronchioles, causing inflammation, swelling, and mucus buildup. It predominantly impacts infants under two years old and is the leading cause of hospitalization for respiratory illness in this age group worldwide (Shay et al., 1999).
Respiratory syncytial virus (RSV) is responsible for approximately 70% of bronchiolitis cases (Hall et al., 2009). In the U.S., bronchiolitis results in over 100,000 hospitalizations annually among infants (Stockman et al., 2004).
What is the difference between Croup and Bronchiolitis?
Signs and Symptoms
| Signs and Symptoms |
Croup |
Bronchiolitis |
| Cough Type |
Harsh, barking (seal-like) |
Mild cough progressing to wheezing |
| Breathing Sounds |
Inspiratory stridor (high-pitched on inhalation) |
Wheezing (typically expiratory) |
| Hoarseness |
Common |
Rare |
| Fever |
Sometimes mild |
May be present |
| Other Symptoms |
Symptoms often worsen at night |
Nasal flaring, rapid or labored breathing, feeding difficulties in infants |
Causes and Affected Areas
| Aspect |
Croup |
Bronchiolitis |
| Cause |
Viral infections, mainly parainfluenza viruses |
Viral infections, predominantly respiratory syncytial virus (RSV) |
| Affected Area |
Upper airway: larynx and trachea |
Lower airway: bronchioles (small airways in lungs) |
Diagnosis and Tests
Croup:
- Primarily diagnosed clinically based on symptoms like barking cough and stridor.
- Neck X-rays may show the “steeple sign” (narrowing of the upper airway). (Polic et al., 2016).
- Pulse oximetry to monitor oxygen levels if breathing difficulty is present.
Bronchiolitis:
- Diagnosed mainly through clinical evaluation of wheezing and respiratory distress.
- Pulse oximetry is commonly used to check oxygen saturation.
- Chest X-rays may show hyperinflation or patchy infiltrates but are not routinely necessary. (Ralston et al., 2014).
- Viral nasal swabs (e.g., RSV testing) may be done in hospital settings.
Treatments
Croup:
- Corticosteroids to reduce airway inflammation.
- Nebulized epinephrine for moderate to severe airway obstruction.
- Supportive care including hydration and humidified air.
- Hospitalization in severe cases.
Bronchiolitis:
- Mainly supportive care: hydration, oxygen therapy if needed.
- Suctioning of nasal secretions to ease breathing.
- Hospitalization may be required for severe respiratory distress.
- Corticosteroids and bronchodilators are generally not recommended.
Prevention
Croup:
- No specific vaccine; general viral infection prevention (handwashing, avoiding sick contacts).
- Seasonal awareness as parainfluenza peaks in fall.
Bronchiolitis:
- Preventive measures include good hand hygiene and avoiding exposure to sick individuals.
- RSV prophylaxis (palivizumab) for high-risk infants (premature, congenital heart disease).
- Vaccination against influenza to reduce respiratory infections.
Risk Factors
Croup:
- Age 6 months to 3 years (due to smaller airway size).
- Boys are slightly more affected.
- Exposure to respiratory viruses, especially during fall and early winter.
- Family history of croup may increase risk.
Bronchiolitis:
- Infants under 2 years old, especially under 6 months.
- Prematurity and low birth weight.
- Exposure to cigarette smoke.
- Attendance at daycare or crowded environments.
- Underlying heart or lung conditions.
How do Children Get Croup or Bronchiolitis?
- Both are caused by viral infections that spread through respiratory droplets.
- Transmission occurs via coughing, sneezing, or close contact with infected individuals.
- Children are highly contagious in the first few days of illness.
- Sharing toys or touching contaminated surfaces can also spread viruses.
- Poor hand hygiene and crowded settings increase risk.
How Long Does Croup or Bronchiolitis Last?
|
Condition
|
Typical Duration |
|
Croup
|
Symptoms usually last 3 to 7 days; worst at night
|
| Bronchiolitis |
Symptoms typically last 1 to 2 weeks; gradual improvement
|
- Recovery times vary depending on severity and overall health.
- Cough may persist longer even after other symptoms resolve.
Croup vs Bronchiolitis vs Pneumonia
Croup, bronchiolitis, and pneumonia are all respiratory illnesses but affect different parts of the respiratory system. Croup affects the upper airway, specifically the larynx and trachea, causing a characteristic barking cough, hoarseness, and inspiratory stridor.
Bronchiolitis involves the lower airways; the small bronchioles; leading to wheezing, rapid breathing, and cough, mainly in infants.
Pneumonia affects the lung tissue (alveoli) itself and typically causes fever, chest pain, and a productive cough. While croup is usually mild to moderate, bronchiolitis can range from mild to severe, especially in very young infants. Pneumonia can be severe and often requires antibiotic treatment.
When to Seek Medical Care?
- Seek immediate medical attention if a child with croup or bronchiolitis shows:
- Difficulty breathing (fast or labored breathing, nostril flaring, chest retractions)
- Persistent high fever
- Blue or gray lips or face (cyanosis)
- Extreme lethargy or unresponsiveness
- Poor feeding or dehydration
- Stridor at rest or worsening symptoms despite home care
Frequently Asked Questions
Can croup turn into pneumonia?
While rare, croup can lead to secondary bacterial infections like pneumonia, especially if symptoms worsen or don’t improve.
Can adults get a croup?
Yes, but it is uncommon due to larger airway size and stronger immunity; adult cases tend to be milder (Foley & Hampson, 2019).
Is croup the same as bronchitis?
No. Croup affects the upper airway causing a barking cough and stridor, while bronchitis involves the larger lower airways with a productive cough (Rosen et al., 2021).