Final answer:
Croup, or laryngotracheobronchitis, primarily affects children between 6 months and 3 years old. It is a viral infection characterized by a barking cough and should not be confused with bacterial pertussis or whooping cough.
Step-by-step explanation:
The peak age for laryngotracheobronchitis, commonly known as croup, is in children between 6 months and 3 years of age. Croup is a respiratory condition characterized by a distinctive barking cough, stridor, and hoarseness, and it typically occurs due to viral infections. While the information provided discusses other respiratory illnesses and pertussis, it is important to note that pertussis and croup, despite both affecting the respiratory system, are different conditions caused by different organisms; pertussis is a bacterial infection caused by Bordetella pertussis, while croup is usually caused by a virus, often the parainfluenza virus.