Croup is a viral infection that attacks the vocal chords and causes swelling. A fever of less than 104 degrees Fahrenheit usually accompanies this virus, along with the hoarse sounding cough. While it is typically not dangerous, it can cause the vocal chords to swell so badly that breathing is obstructed. When this occurs, the child is typically given steroids to reduce the inflammation. It occurs in children under 6 years old and most get it at least a few times in their life. It is just as contagious as the common cold, so if your child is in daycare, they are much more likely to get it.