Understanding Croup - Basic Information

What Is Croup?

Croup, a viral infection of the voice box (larynx) and windpipe (trachea) associated with signs of a respiratory infection, such as a runny nose or cough, is a very common ailment of childhood.

Usually the first indication is a cough that sounds like the bark of a dog or seal.   Your child may have trouble breathing because the tissue around the larynx is inflamed, constricting the windpipe, and because the bronchial passages are blocked with mucus.   The sound of air being forced through the narrowed airways may produce a hollow, raspy noise, called stridor, with each inhaled breath. But there is no similar sound with exhalation, as in wheezing.

Croup lasts for five or six days and is highly contagious to other children who have not had the disease. It usually affects children between the ages of 3 months and 6 years (the average age is 2 years), whose small windpipes and bronchial passages are most vulnerable to blockage.

Most cases are mild and can be managed at home.   In severe cases or in the case of epiglottitis -- an unrelated bacterial infection of the epiglottis (the tissue flap that covers the trachea when swallowing), whose symptoms can sometimes mimic croup in early stages -- your child may need to be hospitalized. (Epiglottitis is distinguished from croup by drooling, refusal to swallow, and a more ill appearing child who is most comfortable sitting up and leaning forward. This disease is now very rare because there is an immunization against the most common bacteria causing this infection.)

What Causes It?

Most croup cases are caused by a parainfluenza virus.   The disease is transmitted by airborne droplets from an infected child's cough.