Library · Disease
Croup
Make it clearer
Croup is a common respiratory infection in children, typically those under 5. It affects the larynx, where the vocal cords are, the trachea, the tube that runs down toward the lungs, and the bronchi, its branches. It is recognized by two sounds: a barking cough, which sounds like a bark, and stridor, a noise that happens when breathing in.
Here is what goes on inside. The infection draws in white blood cells, the body's defense cells, and the upper part of the airway swells. Think of a straw whose wall thickens on the inside: the opening the air passes through gets narrower and partly blocked. Breathing takes more effort, and the air squeezing through becomes turbulent and noisy. That noise is stridor.
The most common cause is parainfluenza virus, although there are also cases caused by bacteria. And that narrowing can sometimes be seen: on a neck X-ray, which is not done routinely, the narrowed trachea may produce the steeple sign, a tapering shaped like a church steeple.
In brief
Croup is a common respiratory illness, typically of children under 5, that affects the trachea, larynx and bronchi and causes a barking cough and stridor when breathing in.
The infection draws in white blood cells, swells the upper airway and partly blocks it; breathing takes more effort, and the turbulent, noisy airflow is the stridor.
The most common cause is parainfluenza virus, although bacterial cases also occur; a neck X-ray, not done routinely, may show the steeple sign from the narrowed trachea.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingCroup, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated