Introduction
The incidence of cystic fibrosis of the pancreas is unknown; nevertheless, new cases are recognized with increasing frequency. Twelve years ago the number of such patients registered in our clinic was approximately 40, while in 1958 the number was over 500. This trend of increased recognition of the disease has also been observed in other cities and may be due to (1) improved diagnostic tests, (2) education of the medical profession and the public, (3) the recognition of the wide range of clinical manifestations of cystic fibrosis, and (4) an actual increase in the gene frequency of cystic fibrosis in the population.The purpose of this report is to describe our experience with a rapid screening test for the detection of cystic fibrosis as applied to a large number of school children in Worcester, Mass. The screening test is done with the silver nitrate-potassium chromate agar plate developed by