Croup in children

roup develops in more than 80 000 Canadian children each year, making it the second most common cause of respiratory distress in the first decade of life. It affects boys more than girls (1.4:1) and young children between 6 months and 3 years of age more commonly than younger infants, older children and adolescents. Croup is frequently preceded by 24-72 hours of nonspecific cough, rhinorrhea, coryza and fever, with abrupt onset of barky cough, hoarse voice and, often, inspiratory stridor during the night. Croup is caused by a viral infection of the respiratory tract that causes edema and in flam ma tion of the upper airway, and laryngeal mucosa resulting in narrowing in the subglottic region of the airway. Human parainfluenza virus (types 1 and 3) is the most common pathogen, 4 but other causative vi ruses include influenza A and B viruses, respi ra tory syncytial virus, rhinovirus, coronavirus, human metapneumovirus and ad e no vi rus. Predictable seasonal patterns occur; the peak incidence of croup typically appears in late fall.