Epidemiologic Basis of TB Control (Cont’d.)
BCG does little to limit the spread of TB
Most TB control programs base diagnosis of TB on sputum smear results which detect at best 50-60% of true cases
Effective chemotherapy eliminates the spread of TB from an active case, but in general ᡂ contacts are identified before chemotherapy is active.
Comstock GW, Am Rev Respir Dis 138: 479-480, 1988
Colditz GA et al., JAMA 1994; 271;698-702