Tuberculin Skin Testing of Children as an Effective Tool in Tuberculosis Casefinding

Abstract

he marked annual decrease in the number of Tnewly reported cases of active tuberculosis during the past ten years has been accompanied by a similar decreased effectiveness of chest x-ray mass screening as a tool in community tuberculosis casefinding programs. However, during the same period, tuberculin skin testing of pre-school and school age children, followed by a thorough examination of positive reactors and their immediate family contacts, has been found to be an effective casefinding instrument, particularly in the big cities, and especially in the slums and ghettos where high risk immigrants and migrants live in overcrowded and substandard housing. With the continuing decrease in the prevalence of clinical disease and tuberculous infection, the signi.6cance of the positive tuberculin skin test becomes more important, especially among pre-school and school age children, because it has identified the infected high risk population. The younger the child with a positive tuberculin test, especially under the age of six years, the more probable that the source of the infection is in the home, among close household contacts-including babysitters. Older children, particularly teenagers, are more probably infected by a source outside the home, through nonhousehold contacts, eg teachers, group leaders, young adults, etc. The effective productiveness of a tuberculin skin testing program in children in identifying unsuspected active tuberculosis in the community, whether newly diagnosed or previously known, is directly proportional to the size of the tubercuIin reaction, and the thoroughness of the follow-up examinations of contacts to determine the source of infection. Not infrequently, previously known and apparently inactive tuberculosis, with stable chest roentgenograms and fortuitously collected negative sputum cultures, has been found to be active during contact examinations. In mass screening programs, 10 mm or more of induration to PPD-S (Mantoux) is a positive reactor, while 5-9 mm of induration is considered doubtful, and 0-4 mm of induration is read as negative. Much fewer cases of active tuberculosis will be found among the 5-9 mm of induration group and their contacts than among the larger reactor group in mass screening programs. In this issue of Chest, Furcolow and associates (page 618) describe a 17-year experience with annual tuberculin skin testing of school children of various ages in Kansas City. Productivity in