Tuberculin reactors in the general population.

Tuberculin testing as a part of case-finding programs and as an aid in differential diagnosis has become increasingly important in recent years. Formerly the test was little used because it was the general belief that all adults and the majority of children living in urban communities were infected with tubercle bacilli. Veeder and Johnston’ (1915), noted statements were frequent in medical and lay literature to the effect that 90 per cent or more of children are infected with tubercle bacilli by the 14th year. In tracing the authority for such statements, they found them based almost entirely on the figures of Hamburger and Monti2 who, in 1909, reported the results of tuberculin tests on 532 children convalescing from diphtheria and scarlet fever in the wards of a public hospital in Vienna. The figures ranged from 9 per cent reactors at one to two years to 94 per cent reactors at 13 to 14 years. VonPirquet3 reported (1909) the results of tuberculin tests on 1,407 children (including cases of clinical tuberculosis). His figures ranged from 20 per cent reactors at one to two years to 80 per cent at 10 to 14 years. The figures of both Hamburger and VonPirquet were obtained from tests on children of the poorer classes of society in Vienna. Veeder and Johnston (1915), published the results of the VonPirquet cutaneous test on 1,321 children admitted to a hospital (over a period of three years) from the poorer and more congested districts of St. Louis. These were admitted for various causes, including clinical manifestations of tuberculosis. They found reactors ranging from 24 per cent at one to two years to 54 per cent at 12 to 14 years. When those with clinical tuberculosis were excluded the percentage of reactors in the 10 to 14 year age period was only 43 per cent. Slater,4 in 1924, found only 10 per cent reactors to the VonPlrquet test among 1,654 unselected school children, ages six to 16 plus years, in a relatively wealthy farming section of Minnesota. In 1931 he reported 10.4 per cent reactors among a similar group tested with 0.1 mgm. of old tuberculin by the Mantoux method. In 1935 Aronson5 presented the results of a survey of the white population of six rural Michigan counties. The report included the rural sections of Kent County. He used old tuberculin intradermally, 0.01 mgm., followed 48 hours later by 1 mgm. in those who did not react to the first dose. Among the 8,025 persons tested reactors ranged from 6.1 per cent under five years, 17.8 per cent at 10 to 14 years, to 76.4 per cent at 40 years and over. It should be noted that the figures for Kent County alone were somewhat