Is Croup Contagious?

Reviewed on 12/17/2020

What Is Croup?

Croup is caused mostly by viruses, and sometimes bacteria, and it is highly contagious. Croup, a viral respiratory illness, commonly affects children ages six months to three years.
Croup is caused mostly by viruses, and sometimes bacteria, and it is highly contagious. Croup, a viral respiratory illness, commonly affects children ages six months to three years.

Croup (laryngotracheobronchitis) is a viral respiratory illness characterized by high-pitched, noisy breathing (stridor), hoarseness, and barking cough.

Croup commonly affects children ages six months to three years. 

What Are Symptoms of Croup?

Early symptoms of croup include: 

  • Congestion
  • Runny nose
  • Inflammation of the mucus membranes inside the nose (coryza)

After the initial symptoms, croup progresses over 12 to 48 hours and symptoms include:

The cough associated with croup usually goes away in about three days though other symptoms may continue for up to a week and before gradually resolving.

What Causes Croup?

Most cases of croup are caused by viruses. Secondary bacterial infections may occur.

Viruses that cause croup include: 

  • Respiratory syncytial viruses (RSV)
  • Adenoviruses 
  • Parainfluenza viruses
    • Most cases of croup occur in the fall (often in October) or early winter, which coincides with parainfluenza type 1 activity.  
  • Human coronavirus NL63 (HCoV-NL63)
  • Measles (in areas where measles remains prevalent)
  • Rhinoviruses
  • Enteroviruses (especially Coxsackie types A9, B4, and B5, and echovirus types 4, 11, and 21)
  • Herpes simplex viruses 
  • Metapneumoviruses 
  • Influenza viruses (uncommon)

Secondary bacterial infections of croup include: 

Croup may sometimes be caused by bacteria, including Mycoplasma pneumoniae.

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Is Croup Contagious?

Croup is caused mostly by viruses, and sometimes bacteria, and it is highly contagious. Croup is transmitted from person-to-person through respiratory droplets propelled into the air when an infected person coughs or sneezes.

How Is Croup Diagnosed?

Croup is diagnosed based on a patient’s symptoms of high-pitched, noisy breathing (stridor) and barking cough, especially during a period when one of the causative viruses is active in the community. 

Tests may be used to rule out other conditions, such as:

  • Blood tests
    • White blood cell (WBC)
    • Blood urea nitrogen (BUN)
    • Serum bicarbonate 
  • Viral culture and/or rapid diagnostic tests that detect viral antigens 
  • Chest X-ray

What Is the Treatment for Croup?

Mild croup may be treated at home to relieve symptoms and includes:

  • Drinking enough fluids
  • Humidifier/mist
  • Fever reducers 

Medication for mild croup may also include a single dose of oral dexamethasone.

Treatment for moderate to severe croup includes: 

  • Nebulized epinephrine 
  • Dexamethasone
  • Supportive care
    • Adequate fluid intake
    • Humidified air or oxygen
    • Fever reducers 
  • Supplemental oxygen if needed

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Reviewed on 12/17/2020
References
https://www.uptodate.com/contents/croup-clinical-features-evaluation-and-diagnosis

https://www.uptodate.com/contents/management-of-croup