Pulmonary diseases in children.

Respiratory infections in infants and children cause much ill-health and also an 
appreciable mortality. They are found at times in most school-children and 
in infants, especially those in large families and those living in 
poor circumstances. In all respiratory infections the whole respiratory tract is 
involved. For descriptive purposes it is useful to divide these infections 
into upper respiratory-tract infections, in which the infection is predominantly at 
the larynx or above; and lower respiratory-tract infections, in which the 
predominant infection is below the larynx. Acute upper respiratory-tract infections are 
usually viral and the poly-virus infection of coryza is the commonest. 
Acute lower respiratory-tract infections are discussed in two groups: in infants 
under two years of age and in children over two (including 
cystic fibrosis). 