ABSTRACT
Identification of the determinants of respiratory health in childhood and assessment of their relative importance as risk factors are complex problems. More important factors include: degree of allergic immune responsiveness, degree of airway reactivity, lower respiratory infection experience, and tendency to mucus hypersecretion. Clinical features of all respiratory infections were recorded, and viral and mycoplasmal cultures of upper respiratory secretions performed at the onset of illness. Croup is an illness in which children with signs of acute respiratory infection develop evidence of upper tracheal and perilaryngeal disease with partial airflow obstruction. The incidence of acute respiratory illness is relatively stable over the first 5 years of life at approximately 6-8 respiratory illnesses per child year. Viruses and bacteria are the principal classes of organisms responsible for lower respiratory tract infections in previously healthy individuals. A respiratory virus or M. pneumoniae was isolated from 26% of lower respiratory infection patients in the pediatric practice study.
