Croup, also known as Laryngotracheitis, is a respiratory illness characterized by infection and inflammation of the upper airways. The illness produces respiratory symptoms such as hoarseness, coughing, and a whistling sound when breathing in (stridor).
The most distinctive feature of croup in infants and children is a barking cough, which is often described as seal-like. It occurs most frequently in children aged between 6 months and 3 years and is uncommon in children over 6. Croup accounts for around 1.3 percent of Emergency Department visits each year, with almost half of the patients being under 2 years old. Croup affects boys more frequently than girls, and some reports suggest it is twice as common in boys.
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Types of croup
Viral croup, also called ‘classic croup’, is the type that commonly affects children aged between 6 months and 3 years. It is caused by respiratory viruses and produces viral symptoms such as nasal congestion and fever (temperature exceeding 100.4˚F). Viral croup usually resolves itself without treatment with the cough lasting around 3 days.
Spasmodic croup is sometimes referred to as ‘allergic croup’ and can also affect children aged between 6 months and 3 years. It differs from viral croup in that it always occurs at night. The onset of symptoms is typically brief, often beginning and ending abruptly. Spasmodic croup can recur within the same night and continue for 2 to 4 consecutive nights. There is usually no fever present, but nasal congestion is a common symptom. It occurs most frequently in children from families with a history of allergies.
The symptoms of croup typically begin with:
- Nasal discharge
- Coryza (inflammation of the mucous membrane in the nose)
Symptoms usually progress after 12 to 48 hours to include:
- Barking cough
Croup causes the upper airways to become inflamed and obstructed. As the condition progresses further, the child may suffer increased respiratory distress due to the obstruction.
A child suffering from croup may be anxious and fearful, which can cause the airways to narrow even more and produce more severe symptoms. It is therefore important to reassure the child and to keep them as comfortable as possible to prevent further respiratory distress.
Croup is usually caused by viruses, such as:
- Parainfluenza 1 — the most common cause.
- Parainfluenza 2 — causes the mildest cases.
- Parainfluenza 3, — causes the most severe sporadic cases.
- Influenza — a relatively uncommon cause
- Human Coronavirus
Croup may also be caused by:
- Measles — in areas where the disease has reemerged
- Bacterial infections
Risk factors for developing croup
- Age between 6 months and 3 years
- Male gender
- Family history of croup and/or allergies
- Exposure to fall/early winter parainfluenza epidemics
Croup is a relatively mild and self-limited disease, meaning that it tends to run its course without requiring treatment.
However, there is a possibility of serious complications. In rare cases, croup can result in significant upper-airway obstruction, respiratory distress, and death.
Diagnosis, treatment, and management
In many cases, croup presents as mild enough to require little or no treatment. It is a self-limited illness that usually runs its course and subsides within a week.
Symptoms of croup can be relieved with humidified air and by keeping the child comfortable and calm. It is also important to keep the child hydrated, as severe croup and the accompanying fever can result in fluid loss.
Children suffering from severe respiratory distress from croup may need to be treated with nebulized (inhaled) epinephrine and nebulized or systemic (injected or oral) corticosteroids, both of which are also used to treat asthma.
To help with diagnosing croup or establishing a differential diagnosis, doctors will ask for a detailed history of symptoms. This includes a description of the onset, duration, and progression of symptoms.
Factors that suggest a condition other than croup include:
- A fever that begins with the onset of symptoms — With croup, the fever typically begins after 12 to 48 hours.
- Drooling — This is a common symptom of similar respiratory illnesses such as epiglottitis, which is the inflammation of the flap at the back of the throat underneath the tongue. Drooling is only found in around 10 percent of croup cases.
- Throat pain — Another symptom that is more common in other respiratory illnesses, such as acute epiglottitis, than in croup.
- Difficulty swallowing — Having difficulty swallowing suggests acute epiglottitis or foreign body ingestion, both of which can mimic the symptoms of croup.
- Tovar Padua LJ, Cherry JD. Croup (laryngitis, laryngotracheitis, spasmotic croup, laryngotracheobronchitis, bacterial tracheitis, and laryngotracheobranchopneumonitis) and epiglottitis (supraglottitis). In: Feigin and Cherry’s Textbook of Pediatric Infectious Diseases, 8th Ed, Cherry JD, Harrison GJ, Kaplan SL, Steinbach WJ, Hotez PJ (Eds), Elsevier, Philadelphia 2019. p.175.
- Pruikkonen H, Dunder T, Renko M, et al. Risk factors for croup in children with recurrent respiratory infections: a case-control study. Paediatr Perinat Epidemiol 2009; 23:153.
- Rihkanen H, Rönkkö E, Nieminen T, et al. Respiratory viruses in laryngeal croup of young children. J Pediatr 2008; 152:661.
- Van Bever HP, Wieringa MH, Weyler JJ, et al. Croup and recurrent croup: their association with asthma and allergy. An epidemiological study on 5-8-year-old children. Eur J Pediatr 1999; 158:253.
- Cherry J. D. (1979). The treatment of croup: continued controversy due to failure of recognition of historic, ecologic, etiologic and clinical perspectives. The Journal of pediatrics, 94(2), 352–354. https://doi.org/10.1016/s0022-3476(79)80883-5
- Thompson M, Vodicka TA, Blair PS, et al. Duration of symptoms of respiratory tract infections in children: systematic review. BMJ 2013; 347:f7027.