Nosocomial transmission of tuberculosis from unsuspected disease.

Tuberculosis remains an occupational hazard for hospital employees. A case of acute generalized tuberculosis occurring in a patient with a malignancy who had received corticosteroids was undetected during life and during a gross autopsy examination. Histologic examination of tissue performed one month later was necessary to establish the diagnosis. Of susceptible hospital staff members who were exposed to the index case, infection developed in nine of 56 (16 percent) compared with three of 333 (0.9 percent) unexposed personnel with similar risk but no known exposure (p less than 0.001). This was a 17.8-fold increase in the infection rate for the exposed group. Three employees infected had evidence of active disease: two had pleural effusions and one had cavitary pulmonary infiltrates; six were asymptomatic. The high rate of infection was associated with inadequate air ventilation and exposure to uncontained infectious aerosol. Preventive therapy with isoniazid, high-change-ventilating systems, ultraviolet radiation, and primary barrier systems are recommended methods to reduce the infection risk.