The high incidence of cystic fibrosis in newborn infants, the high mortality in the first year of life if special treatment is not available, and the improvement in mortality when prophylactic pulmonary therapy is added to conventional therapy are the reasons for the urgent search for a sweat test which can be applied routinely to newborn infants.
Incidence
The incidence of cystic fibrosis is unknown, but the estimates1-9 made in the United States indicate that the true incidence is likely to be between one in 1,000 to 1,400 live-born white infants (Table). The incidence of cystic fibrosis in Negro infants is about 1/9 that in white infants. In comparison with estimates for other congenital or hereditary childhood diseases, cystic fibrosis is about one half as common as mongolism; about as common as club foot, dislocation of the hip, or cleft lip; and about ten times as common as phenylketonuria