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What is croup?

"Croup" or "acute laryngotracheobronchitisis" is the term given a set of conditions resulting from a viral infection that affects the respiratory tract in children. The virus mostly infects upper respiratory tract and the cells in the laryngeal epithelium react by producing excessive mucus. The mucus then can dry up and thicken causing the characteristic symptoms of croup. It is not a life threatening disease, but can cause significant respiratory distress.

In most cases croup can be eliminated by effective homecare unless in severe cases where it requires hospitalisation. There are several other conditions that can be confused with croup, which includes foreign bodies in the lungs and the swelling of the epiglottis (Valve like structure with covers the respiratory tract during breathing). These are much more serious conditions.

Croup usually starts as a cold but as the disease progresses it can cause swelling inside the trachea which narrows the respiratory tract causing difficulty in breathing. Symptoms can be frightening for the parent to see the child struggle for air in the middle of the night but is not a cause for undue worry. The proportion of children that need to be hospitalised as a result of croup is less than 2% (US data).

Who gets croup?

Croup is a paediatric condition and prevails among children between 3 months and 6 years old. Symptoms are most severe in children under three years. The incidence of croup is more common during the winter months of the year. There is a gender difference in the occurrence of croup and males tend to get it more often than females.

Most healthy children who come into contact with infectious agents that cause croup will not necessarily get infected by them. As children get older they outgrow croup as their respiratory tracts matures, it is very uncommon for adults to present with croup.

Causative and risk factors

The most common causative virus strains are:

  1. Parainfluenza virus (type 1 and 3)
  2. Respiratory syncytial virus (RSV)
  3. Adenovirus
  4. Influenza virus (flu)(types A & B )
  5. Measles virus
  6. Echovirus

Occasionally croup can be caused by an allergic reaction where the respiratory epithelial lining react in the same way to the allergen as they would to the virus. Sometimes early signs of asthma can have croup like manifestations.
Smoke can worsen croup and it is essential to remove the child to a non-smoking area if there are smokers around.

Signs and symptoms

Symptoms have an abrupt onset and are preceded by rhinorrhoea (runny nose) and sniffles for about 1-2 days. . On examination the child will usually present with a "Stridor" which is a high pitched rough sound during inhalation (breathing in). This is accompanied by a tight sounding cough (which mimics a barking seal). The symptoms increase at night (getting worse on several consecutive nights in a row) and subside during the day. The child's voice will be very hoarse and there is usually low-grade fever alongside as well.

Rarely due to poor air entry into the lungs, the child may develop signs of low oxygen, which manifests as cyanosis (lips can turn blue). This constitutes a medical emergency and warrants prompt medical attention.


Diagnosis is based on the history and symptoms. X-rays of the neck and chest show changes associated with swelling of the larynx and assist Doctors in management. Certain conditions such as epiglottitis and diptheria can mimic croup.

Complications associated with croup

Rarely croup can lead to some complications such as otitis media (middle ear infection), pneumonia and adenitis. These occur secondary to extension of infective processes. Approximately 15% of US children with viral croup develop mild complications most commonly in the lower respiratory tract and middle ear.

Managing croup
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