care for a high proportion of people who are at increased risk of tuberculosis (e.g., those who are unemployed or homeless, recent immigrants from developing countries, and individuals with HIV infection or AIDS).

Workers’ risk of tuberculosis is also affected by employer and community efforts to prevent the spread of tuberculosis. Investigations of workplace outbreaks of tuberculosis have typically identified lapses in infection control measures as probable contributors to transmission. As discussed in Chapter 6, much of the support for the effectiveness of tuberculosis control measures comes from outbreak investigations and subsequent studies of the implementation of administrative controls and other measures. In workplaces that have many workers in direct contact with infectious individuals, employers’ policies and procedures affect the likelihood that employees will acquire tuberculosis infection or disease on the job.

Although Chapter 6 points to the importance of careful and alert application of protocols for identifying those likely to have infectious tuberculosis, application of such protocols does not guarantee that all cases will be promptly identified. Unsuspected and undiagnosed tuberculosis is the primary threat to workers.

The committee’s conclusions about the workplace risk of tuberculosis must be understood against this backdrop. If the conclusions highlighted below are taken out of context, the occupational risk of tuberculosis may be misunderstood. Although the committee judged that the following conclusions were reasonably supported by the available literature, it notes that most of the studies that it consulted involved hospitals and were inconsistent in methods, reporting, and results.

Conclusions

Through at least the 1950s, health care workers were at higher risk from tuberculosis than others in the community. Before the development of effective treatments for the disease, several studies documented very high rates of infection for nurses and physicians. The available data do not allow conclusions about the historical risk to other categories of workers covered by the 1997 proposed OSHA rule.

Despite the availability of effective treatments, the last decade and a half has shown that tuberculosis remains a threat to health care and other workers, especially when workplaces neglect basic infection control measures and when multidrug-resistant disease is present. The primary risk today comes from patients, inmates, and others with unsuspected and undiagnosed infectious tuberculosis. Even with good tuberculosis control measures, some workers will still be exposed to people with unsuspected infectious disease, particularly in communities where the disease is common.

Available data suggest that where tuberculosis is uncommon or where basic infection control measures are in place, the occupational risk to health care work-



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