The incidence of tuberculosis in physicians was determined by mailed questionnaire. Since 1950 tuberculosis infection preceding entry into medical school has decreased by 73%; at the same time, infection after beginning medical school decreased by 78%. Tuberculin conversion rates among recent graduates exceeded 1% per year, and age-specific infection rates among physicians were at least twice the US average. Tuberculosis developed in nearly one in ten physicians infected after medical school entry; in two thirds, disease preceded or coincided with recognized tuberculin positivity. No tuberculosis occurred in physicians who used isoniazid chemoprophylaxis, but two thirds of tuberculin-negative physicians did not have annual skin tests, 56% of known recent converters used no chemoprophylaxis, and 25% of those initiating isoniazid prophylaxis did not complete a 12-month course. The Bacillus Calmette-Guérin vaccine recipients had 80% less tuberculosis than unimmunized physicians infected after beginning medical school.
(JAMA 241:33-38, 1979)
Barrett-Connor E. The Epidemiology of Tuberculosis in Physicians. JAMA. 1979;241(1):33–38. doi:10.1001/jama.1979.03290270023014