Croup, also known as laryngotracheobronchitis, is a type of respiratory infection that is usually caused by a virus. The infection leads to swelling inside the trachea, which interferes with normal breathing and produces the classic symptoms of "barking/brassy" cough, inspiratory stridor and a hoarse voice. Fever and runny nose may also be present. These symptoms may be mild, moderate, or severe. Often it starts or is worse at night and normally lasts one to two days.Croup can be caused by a number of viruses including parainfluenza and influenza virus. Rarely is it due to a bacterial infection. Croup is typically diagnosed based on signs and symptoms after potentially more severe causes, such as epiglottitis or an airway foreign body, have been ruled out. Further investigations, such as blood tests, X-rays and cultures, are usually not needed.Many cases of croup are preventable by immunization for influenza and diphtheria. Most cases of croup are mild and the child can be treated at home with supportive care. Croup is usually treated with a single dose of steroids by mouth. In more severe cases inhaled epinephrine may also be used. Hospitalization is required in one to five percent of cases.Croup is a relatively common condition that affects about 15% of children at some point. It most commonly occurs between six months and five years of age but may rarely be seen in children as old as fifteen. It is slightly more common in males than females. It occurs most often in autumn.
Before vaccination, croup was frequently caused by diphtheria and was often fatal. This cause is now very rare in the Western world due to the success of the diphtheria vaccine. Signs and symptoms
Croup is characterized by a "barking" cough, stridor, hoarseness, and difficult breathing which usually worsens at night. The "barking" cough is often described as resembling the call of a sea lion. The stridor is worsened by agitation or crying, and if it can be heard at rest, it may indicate critical narrowing of the airways. As croup worsens, stridor may decrease considerably.Other symptoms include fever, coryza (symptoms typical of the common cold), and indrawing of the chest wall–known as Hoovers sign. Drooling or a very sick appearance can indicate other medical conditions, such as epiglottitis or tracheitis. Causes
Croup is usually deemed to be due to a viral infection. Others use the term more broadly, to include acute laryngotracheitis (laryngitis and tracheitis together), spasmodic croup, laryngeal diphtheria, bacterial tracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis. The first two conditions involve a viral infection and are generally milder with respect to symptomatology; the last four are due to bacterial infection and are usually of greater severity. Viral
Viral croup or acute laryngotracheitis is most commonly caused by parainfluenza virus (a member of the paramyxovirus family), primarily types 1 and 2, in 75% of cases. Other viral causes include influenza A and B, measles, adenovirus and respiratory syncytial virus (RSV).