ThedaCare Health Matters
The respiratory tract seems to be more prone to illness in the fall and winter months. Different illnesses affect different portions of the respiratory system. Croup is a respiratory illness that causes inflammation and swelling of the upper portion of the trachea and larynx and is known for its characteristic cough, which sounds like a seal barking.
Croup affects children between 6 months and 3 years old, although older children can be affected. It is primarily a viral illness that can be caused by different viruses but most commonly by a family of viruses known as parainfluenza viruses. There is no vaccine for parainfluenza viruses.
Young children are more susceptible to this problem because the diameter of the upper airway (trachea and larynx) is small. The virus tends to cause swelling just below the vocal cords. Since the opening to the airway is naturally small at this point, a small amount of swelling can cause significant narrowing. This causes the barking cough and can cause difficulty getting air to flow adequately.
When adults with larger diameter airways become infected with the same virus, they tend to have just cold symptoms since the swelling does not cause significant narrowing of their airway.
Interestingly, Croup tends to be a night-time illness. It is common for children to go to bed with very minimal symptoms and then wake during the night with cough, hoarseness, low grade fever and trouble breathing. The wind pipe can be narrowed enough that breathing can make a noise as air passes through this area known as stridor.