facilities where recent Centers for Disease Control and Prevention (CDC) guidelines for infection control have been implemented is usually not substantially greater than the risk incurred by these individuals in the communities in which they reside.

The risk to infected health care workers of progression to tuberculous disease (tuberculosis) is lower than often stated; the risk of mortality for immunocompetent individuals harboring drug-susceptible organisms is negligible. The risks of tuberculous disease and mortality in Mycobacterium tuberculosis-infected health care workers is probably no higher than that of individuals in the general population. Overall, the risk of tuberculosis in individuals who become infected as adults is probably of the order of 5 percent. Nearly all of the tuberculosis mortality in the United States today is accounted for by individuals who fail to be diagnosed or treated in timely fashion, who are immunocompromised (usually by human immunodeficiency virus [HIV] infection), or who suffer from multidrug-resistant tuberculosis.

INTRODUCTION

In an era of recently resurgent tuberculosis and accompanying concern about the occupational tuberculosis risk of health care workers, the Institute of Medicine has been asked by the U.S. Congress to study the magnitude of this occupational risk and the potential impact on it of a newly proposed rule regulating the environment in which care of tuberculosis patients is conducted. At the present time, health care workers account for about 3 percent of the cases of tuberculosis reported in the United States (1).

Charge to the Reviewer

This paper reviews the published medical literature relevant to the occupational tuberculosis risks of American health care workers. It was commissioned by the Institute of Medicine Committee on Regulating Occupational Exposure to Tuberculosis. The charge of this committee was to prepare a state-of-the-art literature review addressing the following questions:

Are health care workers (and workers at other sites covered by the proposed OSHA regulations) at a greater risk of infection, disease, and mortality due to tuberculosis than the general community within which they reside? If so, what is the excess risk due to occupational exposure? Can the occupationally acquired risk be quantified for different work environments and different job classifications?

Determinants of Tuberculosis Risks

Consideration of the occupational tuberculosis risk of health care workers must be done in two parts: the risk of infection and the risk of



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