[Yield from studying the contacts of patients with tuberculosis]

Between march '88 and august '89 a total number of 437 contacts (CT) with 69 patients with tuberculosis were analyzed. According to the bacteriological status of the index case the observations were distributed into: Group I (197) CT with patients with positive sputum AFB stain test; Group II (24) CT with cases with positive sputum culture but negative AFB stain; and Group III (216) CT with cases with histologic diagnosis or cases in children. Following identical criteria and according to the bacteriologic situation of the Source case, we grouped the contacts on groups A (246), B (17), and C (174). A clinical history, thorax radiography, and tuberculin test with 2 UT of PPD-RT 23 were performed in all CT cases. Tuberculin reaction was equal or greater than 6 mm in 45% (88/197), 25% (6/24), and 36% (77/216) of groups I, II, and III respectively. This reaction was also positive in 49% (121/246), 23% (4/17), and 26% (46/174) of groups A, B, and C respectively. Sixteen new cases of tuberculosis were discovered among which we identified 5 new source cases. A second tuberculin test was performed in 44% (116/266) of CT with a previous negative test, and in this population we observed 16 conversions. It is demonstrated: 1) a high yield in the detection of infection/tuberculous disease; 2) the analysis of CT in group A provided the highest index of tuberculous infection, and 3) revision of CT of groups II and III provided most of the new cases of disease as well as the identification of 5 new source cases.