MANAGEMENT OF HEALTH-CARE WORKERS AFTER INADVERTENT EXPOSURE TO TUBERCULOSIS - A GUIDE FOR THE USE OF PREVENTIVE THERAPY

Objective: To quantify the protection of previously infected persons f rom developing tuberculosis after intense exposure. Setting: 6 hospita ls and 22 nursing homes in which heavy tuberculosis exposure had occur red. Measurements: Results of tuberculin skin tests before and after e xposure and the development of tuberculosis among known reactors, both converters and nonconverters. Intervention: All converters were given preventive therapy with isoniazid as soon as they could be identified . Nonconverters and previously known reactors were not treated. Result s: In 6 hospital outbreaks, largely aborted by prompt preventive thera py, 98 of 336 nonreactors (29%) showed skin test conversion, and, befo re therapy could be started, 19 (19% [95% CI, 12% to 29%]) had develop ed tuberculosis. No tuberculosis developed among the 238 nonconverters (0% [CI, 0% to 1.5%]) or the 76 known reactors who were not treated ( 0% [CI, 0.5% to 2%]). Tuberculosis developed in 5 of 209 known reactor s (2.4% [CI, 0.8% to 5.5%]) in 22 nursing homes with heavy exposure, l ittle more than 10 of 921 known reactors (1.1% [CI, 0.5% to 2%]) in 76 homes where there was no exposure (P = 0.17). Conclusions: Healthy pe rsons who remain nonreactive to tuberculin after heavy exposure have e scaped infection and require no chemotherapy. However, if exposure is discovered immediately, it is wise to start preventive therapy in part icularly heavily exposed nonreactors-and discontinue it if the skin te st result is still negative at 3 months. Persons who react after expos ure fall into three groups: 1) converters, in whom the risk for tuberc ulosis warrants preventive chemotherapy, regardless of age; 2) reactor s with no preexposure test results, who should be treated as converter s; and 3) previously known reactors, in whom the risk for tuberculosis generally is too slight to warrant therapy. However, those who are yo unger than age 35 years, have human immunodeficiency virus infection, are receiving cancer chemotherapy or long-term corticosteroid therapy, or are otherwise immunocompromised should be considered for preventiv e therapy, regardless of the exposure.