Final answer:
Croup is an acute viral infection that occurs in infants before 3 years of age. It causes vocal cord swelling, voice loss, hypoxia, and possible choking.
Step-by-step explanation:
The condition referred to as croup is an acute viral infection that is usually seen in infants before 3 years of age. It occurs after an upper respiratory infection (URI) and causes vocal cord swelling, voice loss, hypoxia, and possible choking. Croup is commonly caused by the parainfluenza virus, specifically the type 1 and 2 strains.