Summary

Tuberculosis is a treatable, communicable disease that has two general states: latent infection and active disease. With few exceptions, only those who develop active tuberculosis in the lungs or larynx can infect others, usually by coughing, sneezing, or otherwise expelling tiny infectious particles that someone else inhales.

Although tuberculosis is still a major killer in poor countries, 50 years of effective drug treatment has greatly reduced the toll that the disease takes in developed countries. Nonetheless, after more than 30 years of declines in reported tuberculosis cases and deaths, the mid-1980s and early 1990s saw a reversal of that trend in the United States. This resurgence of tuberculosis, which included several outbreaks of the disease among hospital patients and workers, prompted considerable concern among health care workers, administrators, public health professionals, and policymakers. Renewed public and private efforts to control the disease followed. These efforts included the initiation of a rulemaking process by the federal Occupational Safety and Health Administration (OSHA) that led, in 1997, to the publication of proposed regulations on occupational tuberculosis.

In November 1999, the U.S. Congress requested that the National Academy of Sciences undertake a short-term study to examine the risk of tuberculosis among health care workers and the possible effects of federal guidelines and regulations intended to protect workers from this risk. Between April and September 2000, a committee of the Institute of Medicine (IOM), the health policy arm of the Academy, investigated three questions:



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Tuberculosis in the Workplace Summary Tuberculosis is a treatable, communicable disease that has two general states: latent infection and active disease. With few exceptions, only those who develop active tuberculosis in the lungs or larynx can infect others, usually by coughing, sneezing, or otherwise expelling tiny infectious particles that someone else inhales. Although tuberculosis is still a major killer in poor countries, 50 years of effective drug treatment has greatly reduced the toll that the disease takes in developed countries. Nonetheless, after more than 30 years of declines in reported tuberculosis cases and deaths, the mid-1980s and early 1990s saw a reversal of that trend in the United States. This resurgence of tuberculosis, which included several outbreaks of the disease among hospital patients and workers, prompted considerable concern among health care workers, administrators, public health professionals, and policymakers. Renewed public and private efforts to control the disease followed. These efforts included the initiation of a rulemaking process by the federal Occupational Safety and Health Administration (OSHA) that led, in 1997, to the publication of proposed regulations on occupational tuberculosis. In November 1999, the U.S. Congress requested that the National Academy of Sciences undertake a short-term study to examine the risk of tuberculosis among health care workers and the possible effects of federal guidelines and regulations intended to protect workers from this risk. Between April and September 2000, a committee of the Institute of Medicine (IOM), the health policy arm of the Academy, investigated three questions:

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Tuberculosis in the Workplace Are health care and selected other categories of workers at a greater risk of infection, disease, or mortality due to tuberculosis than others in the communities in which they reside? What is known about the implementation and effects of the 1994 Centers for Disease Control and Prevention (CDC) guidelines for the prevention of tuberculosis in health care facilities? What will be the likely effects on rates of tuberculosis infection, disease, and mortality of an anticipated OSHA standard to protect workers from occupational exposure to tuberculosis? The committee’s charge from Congress for this limited study did not include the development of recommendations for regulatory policy. It also did not include an evaluation of the costs or cost-effectiveness of implementing a standard. Overall, the committee concludes that tuberculosis remains a threat to some health care, correctional facility, and other workers in the United States. Although the risk has been decreasing in recent years, vigilance is still needed within hospitals, prisons, and similar workplaces, as well as in the community at large. Fortunately, tuberculosis control measures recommended by the CDC in response to tuberculosis outbreaks in health care facilities appear to have been effective. Available evidence suggests that where tuberculosis is uncommon or where basic infection control measures are in place, the occupational risk to health care workers of tuberculosis now approaches community levels, which have been declining. The primary risk to workers today comes from patients, inmates, or others with unsuspected and undiagnosed infectious tuberculosis. The committee also concludes that an OSHA standard on occupational tuberculosis can have a positive effect if it meets three basic conditions: (1) it is consistent with tuberculosis control measures that appear to be effective, (2) it increases or sustains the level of compliance with those measures, and (3) it allows appropriate flexibility for organizations to adopt tuberculosis control measures appropriate to the level of risk facing workers. The committee expects that a standard will meet the first two conditions by sustaining or increasing the use of effective tuberculosis control measures. The committee is, however, concerned that if a final OSHA standard follows the 1997 proposed rule, it may not meet the third condition of allowing reasonable flexibility to adopt measures appropriate to the level of risk. CDC GUIDELINES AND THE PROPOSED OSHA RULE 1994 CDC Guidelines In 1994, CDC published its most extensive guidelines for preventing the transmission of tuberculosis in health care facilities (including health

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Tuberculosis in the Workplace care units in prisons, jails, and certain other settings). The guidelines present a three-level hierarchy of tuberculosis control recommendations comprising administrative controls (in particular, protocols for early identification, isolation, and treatment of individuals with infectious tuberculosis), engineering controls (in particular, negative-pressure ventilation of isolation rooms for patients with infectious tuberculosis), and personal respiratory protection (primarily use of specially designed facemasks to prevent inhalation of infectious particles). The CDC guidelines, which followed statements issued in 1982 and 1990, also set forth a risk assessment process that defines five categories of facilities (or areas of facilities) based on the risk of tuberculosis transmission. The guidelines recommend fewer tuberculosis control measures for the facilities in the “minimal” and “very low” risk categories. The risk assessment process for a facility covers the profile of tuberculosis in the community, the numbers of tuberculosis patients examined or treated in different areas of the facility, and the tuberculin skin test conversion rates for workers in different areas of the facility or in different job categories. The process also takes into account evidence of person-to-person transmission of tuberculosis resulting in active disease as well as information from medical record reviews or workplace observations that suggests possible problems in tuberculosis control measures. In the summer of 2000, CDC began a reassessment of its guidelines for health care facilities, and the results are expected in mid-2002. 1997 Proposed OSHA Rule When the committee began work in April 2000, OSHA expected to publish the final standard on occupational tuberculosis in July. Subsequently, OSHA indicated that publication would likely occur by the end of the year 2000, which would follow the committee’s final meeting in September 2000. Thus, the committee had to undertake its analyses without knowing the content of the final regulations. It is possible that the new Administration will not issue any final standard. By law, OSHA can directly regulate only private employers and, with certain restrictions, federal agencies. Through agreements with states that choose to participate, OSHA regulations may also be applied to employees of state and local governments. About half the states have entered into such agreements. In its 1997 proposed rule on occupational tuberculosis, OSHA followed the 1994 CDC guidelines in most respects. Also, OSHA concluded that the CDC guidelines in their original form were not specific and direc-

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Tuberculosis in the Workplace tive enough to be adopted directly as a regulatory standard. The proposed rule, therefore, differs from the CDC guidelines in certain ways. First, the proposed rule is written to be enforced and, therefore, tends to be more specific and directive than the CDC guidelines. Second, it would cover a broader group of employers and employees. Third, it is intended to protect employees and not, for example, patients, prisoners, or visitors. Fourth, it sets forth very restrictive criteria for defining “low-risk” employers that would not be expected to implement all the rule’s requirements. The 1997 proposed OSHA rule defines a category of employers that would be exempt from some of its requirements, but the qualifying criteria are narrower than those set forth in the 1994 CDC guidelines. Specifically, a facility must neither admit nor provide medical services to individuals with suspected or confirmed tuberculosis, it must have had no confirmed cases of infectious tuberculosis during the previous 12 months, and it must be located in a county that has had no confirmed cases of infectious tuberculosis during 1 of the previous 2 years and less than six cases during the other year. Even if a facility had admitted no tuberculosis patients in the preceding 12 months, had no tuberculosis cases in its service area, and had a policy of referring those with diagnosed or suspected tuberculosis, that facility could not qualify for this “lower risk” category if the surrounding county had reported one case of tuberculosis in each of the preceding 2 years. ASSESSMENT AND CONCLUSIONS Context: Changing Tuberculosis Case Rates and Community and Workplace Responses The committee’s conclusions need to be understood in context. This context includes the changing epidemiology of the disease over the past two decades, the evolution of community and institutional responses to the perceived threat of tuberculosis, and the persistence of geographic variations in community levels of tuberculosis. Resurgent Tuberculosis, 1985–1992 Between 1985 and 1992, reported cases of tuberculosis increased by 20 percent, from 22,201 in 1985 to 26,673 in 1992. The case rate per 100,000 population increased by more than 12 percent, from 9.3 in 1985 to 10.5 in 1992. The number of deaths rose from 1,752 in 1985 to 1,970 in 1989. In the early 1980s, about 0.5 percent of new tuberculosis cases were resistant to the two major antituberculosis drugs, isoniazid and rifampin. By 1991, that figure had risen to 3.5 percent.

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Tuberculosis in the Workplace In addition, during the late 1980s and early 1990s, several U.S. hospitals experienced outbreaks of tuberculosis that affected both patients and employees. Some outbreaks involved a particularly lethal combination of multidrug-resistant disease and people with suppressed immune systems, most often related to HIV infection. Outbreaks also occurred in prisons and other workplaces serving people at increased risk of tuberculosis. Lack of Preparation In general, public health departments, health care facilities, prisons, and similar organizations were not prepared to cope with the resurgence of tuberculosis in the mid-1980s. After years of effective treatment and declining case rates, tuberculosis control measures were not a priority in either the community or the workplace. The HIV/AIDS epidemic and its interaction with tuberculosis were not well documented or understood. Similarly, the threat of multidrug-resistant tuberculosis resulting from incomplete treatment of the disease had yet to be clearly appreciated. Workplace outbreaks of tuberculosis were often associated with lapses in infection control measures. Rebuilding Capacity The resurgence of tuberculosis in communities and the outbreaks of the disease in workplaces prompted a range of public and private responses. Congress revived federal funding for tuberculosis control programs, which had virtually disappeared in the 1970s. States and some cities and counties also began to rebuild programs that had been neglected or dismantled. These programs focused on groups at increased risk of tuberculosis such as people with HIV infection or AIDS, and they emphasized directly observed therapy for individuals with active tuberculosis. Hospitals, prisons, and perhaps other institutions, especially those affected by outbreaks and those located in high-risk areas, improved their infection control programs. Guidelines and Regulations In 1990, CDC issued new guidelines for tuberculosis control measures in health care facilities. In 1993, in response to calls from health care and other workers, OSHA began to enforce some tuberculosis control measures under its general powers to protect worker safety and under other regulations related to airborne hazards. In 1994, the agency began a formal rulemaking process to develop specific regulations on occupational tuberculosis. Also in 1994, CDC issued a major revision of its 1990

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Tuberculosis in the Workplace guidelines for the prevention of transmission of tuberculosis in health care facilities. OSHA published a proposed rule on occupational tuberculosis in 1997 and solicited comments on the rule in 1998 and again in 1999. In addition, some state licensure agencies and private accrediting organizations required tuberculosis control measures. Decreasing Rates of Disease The epidemiology of tuberculosis has changed substantially since the early 1990s. In 1993, the trend of increasing tuberculosis case rates began to reverse, and declines have now been recorded for 7 successive years. Tuberculosis case rates reached new lows in 1999, when CDC reported a rate of 6.4 per 100,000 population, a 35 percent drop since 1992. Cases of multidrug-resistant disease have also decreased; in 1999, they accounted for just 1.2 percent of cases. In general, fewer cases of tuberculosis and less multidrug-resistant disease mean less risk for nurses, doctors, correctional officers, and others who work for organizations that serve people who have tuberculosis or who are at increased risk of the disease. Continuing Geographic Variation Despite the general decline in tuberculosis rates in recent years, a marked geographic variation in tuberculosis case rates persists, which means that workers in different areas face different potential risks. Among metropolitan statistical areas, 1999 case rates varied from 1.3 per 100,000 population in Omaha to 17.7 per 100,000 in New York City and 18.2 per 100,000 in San Francisco. Between 1994 and 1998, six states—California, Florida, Illinois, New Jersey, New York, and Texas—accounted for 57 percent of tuberculosis cases but had just under 40 percent of the U.S. population. These states also account for a large proportion of people with risk factors for the disease, notably, HIV infection and immigration from countries with a high prevalence of tuberculosis. More than 40 percent of tuberculosis cases reported in the United States in 1999 involved people born in other countries, primarily Mexico, the Philippines, and Vietnam. Conclusions One problem facing the IOM committee as well as CDC and OSHA was the lack of prospective, controlled studies documenting the effectiveness of specific protective measures in preventing the transmission of tuberculosis in the workplace. Most studies of these protective measures are retrospective or observational, and they are inconsistent in their methods and reporting. The studies typically involve organiza-

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Tuberculosis in the Workplace tions—mainly hospitals—that experienced tuberculosis outbreaks and then implemented multiple control measures in a fairly short period of time. No national data on occupational risk of tuberculosis infection are available, and data from surveys, outbreak studies, and other sources are subject to various biases. Data are especially sparse for workplaces other than hospitals. This lack of information is troubling because many of these facilities serve people at increased risk of active tuberculosis—including people who are unemployed, homeless, or poor; people with human immunodeficiency virus (HIV) infection or AIDS or substance abuse problems; and recent immigrants from countries with high rates of tuberculosis. These other workplaces may lack the resources and expertise available to hospitals to assess the risk to workers and undertake appropriate precautions. External oversight may also be more limited. After reviewing scientific and other literature, considering discussions held during the committee’s public meetings, and drawing on its members’ experience and judgment, the committee reached several conclusions in response to the questions posed to it. Again, the committee’s charge and resources did not provide for consideration of policy options and recommendations. Question 1: Are health care and selected other categories of workers at greater risk of infection, disease, or mortality due to tuberculosis than others in the community in which they reside? Through at least the 1950s, health care workers were at higher risk from tuberculosis than others in the community. Currently available data suggest where tuberculosis is uncommon or where basic infection control measures are in place, the occupational risk to health care workers of tuberculosis infection now approaches the level in their community of residence. Tuberculosis risk in communities has been declining since 1993. Overall, rates of active tuberculosis among health care workers are similar overall to those reported for other employed workers. Data do not allow comparisons of mortality risk, but health care workers and others with compromised immune function are at high risk of death if they contract multidrug-resistant disease. The primary risk to health care, correctional, and other workers now comes from patients, inmates, or clients with unsuspected, undiagnosed infectious tuberculosis. Risk is influenced by the prevalence of tuberculosis in the community that the workplace serves and by the extent and type of worker’s contact with people who have infectious tuberculosis. The available data do not allow precise quantification of the risk to health care workers or conclusions about the historical or current risk to other categories of workers covered by the 1997 proposed OSHA rule.

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Tuberculosis in the Workplace Question 2: What is known about the implementation and effects of the 1994 CDC guidelines for the prevention of tuberculosis in health care facilities? Conclusions about the implementation and effect of the CDC guidelines must be read within the larger context of the social response to resurgent tuberculosis. The actions recommended in the CDC guidelines are consistent with general standards of good infection control, and the 1994 guidelines were built on a series of earlier government and professional recommendations. In addition, by the mid-1990s, OSHA and some state agencies were also requiring many of the same basic measures. Implementation Data from surveys, facility inspections, and other sources indicate that institutional departures from recommended tuberculosis control policies and procedures were common, if not the norm, in the late 1980s and the early 1990s. By the mid-1990s, hospitals, and, less clearly, other health care organizations and correctional facilities began to take tuberculosis control measures more seriously. The adoption of written tuberculosis control policies does not, however, always translate into consistent day-to-day practice. Implementation is probably most complete for administrative controls including procedures for promptly identifying, isolating, diagnosing, and adequately treating people with active tuberculosis. For engineering controls, available data suggest that the rate of installation of negative-pressure isolation rooms has increased, but not all in-use rooms are assessed on a daily basis to ensure that they remain under negative pressure. Information about personal respiratory protection programs is very limited. It suggests that most hospitals have been providing some kind of protection and have been updating the equipment provided as new options, such as the N95 respirator, have been developed and certified by the National Institute for Occupational Safety and Health. Effects Overall, the measures recommended by CDC in 1994 and earlier to prevent the transmission of tuberculosis in health care facilities have contributed to ending hospital outbreaks of tuberculosis and preventing new ones. Studies of outbreaks as well as logic and biologic plausibility support CDC’s stress on administrative controls, particularly the rigorous application of protocols for the prompt identification and isolation of people with signs and symptoms suspicious for infectious tuberculosis. Studies of outbreaks and modeling exercises suggest that engineering controls also make a contribution in limiting the transmission of tubercu-

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Tuberculosis in the Workplace losis. Available information suggests that most of the benefit of control measures comes from administrative and engineering controls. Modeling studies support the tailoring of personal respiratory protections to the level of risk faced by workers—that is, more stringent protection for those in high-risk situations and less stringent measures for others. Although control measures have helped to end workplace outbreaks of tuberculosis and prevent transmission of the disease, these measures cannot prevent all types of worker exposure to tuberculosis. In areas with moderate to high levels of tuberculosis, some worker exposure to patients with unsuspected infectious tuberculosis can be expected. Not all infectious individuals have easily recognized symptoms or signs of the disease, so workers may be exposed to them for a period before tuberculosis is suspected, a diagnosis is made, and precautions are initiated. Conscientious implementation of tuberculosis control measures does not guarantee that transmission will never occur, but it appears to reduce risk significantly, especially in high-prevalence areas. Question 3: What will be the likely effects on rates of tuberculosis infection, disease, and mortality of an anticipated OSHA standard to protect workers from occupational exposure to tuberculosis? Because the committee had to work without access to the final OSHA regulations on occupational tuberculosis, it could not be certain of whether or how the final standard would differ from the 1997 proposed rule or from the 1994 CDC guidelines. Therefore, rather than concentrate narrowly on individual features of the proposed rule, the committee decided to consider more generally the conditions that would need to be met for a standard to have positive effects on tuberculosis infection, disease, or mortality. It identified three such conditions. First, implementation of workplace tuberculosis control measures as recommended by CDC and proposed by OSHA must contribute meaningfully to the prevention of transmission of Mycobacterium tuberculosis in hospitals and other covered workplaces. Second, an OSHA standard must sustain or increase the level of adherence to workplace tuberculosis control measures, especially in high-risk institutions and communities. Third, an OSHA standard must allow reasonable adaptation of tuberculosis control measures to fit differences in the levels of risk facing workers. Overall, the committee expects that the first of the conditions outlined above—that tuberculosis control measures are effective—will be met for hospitals and possibly correctional facilities. Insufficient information is available to assess the effectiveness of control measures in other workplaces. The committee expects that the second condition will also be met; that is, an OSHA standard will sustain or increase the level of compliance with mandated tuberculosis control measures. A standard is likely to motivate

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Tuberculosis in the Workplace more organizational adherence to control measures than can be achieved by voluntary guidelines. A standard is also likely to be clearer, more hazard specific, and easier to use than the other legal strategies available to OSHA. In addition, by providing a firmer basis for OSHA enforcement actions, a standard should put workers on stronger ground in identifying and challenging an employer’s inadequate implementation of mandated tuberculosis control measures. The committee is concerned, however, that if an OSHA standard follows the 1997 proposed rule, it may not meet the third condition of allowing organizations reasonable flexibility to adopt tuberculosis control measures appropriate to the level of risk facing workers. The 1997 proposed rule defines a category of employers that would be excused from some of the rule’s requirements, but the criteria defined are very narrow and would likely subject too many low-risk organizations to the rule’s full scope. In addition, as an indicator of tuberculosis risk in the community, the proposed rule would require use of county-level data to assess community risk, even though a facility’s service area might be quite different and have a much different incidence of tuberculosis. To the extent that an OSHA standard inflexibly extends requirements to institutions that are at negligible risk of occupational transmission of M. tuberculosis, the standard is unlikely to benefit workers at the same time that it would impose significant costs and administrative burdens on covered organizations and absorb institutional resources that could be applied to other, potentially more beneficial uses. The committee also concludes that OSHA’s 1997 estimates overstated the number of infections, cases of disease, and deaths due to tuberculosis that would be averted by adoption of the 1997 proposed rule. (The committee did not have access to OSHA’s recently revised estimates.) Tuberculosis case rates are down substantially from 1994 and the earlier years used for the estimates, and implementation of community and workplace tuberculosis control measures appears to be considerably improved. Recent data on tuberculosis infection are limited but indicate low levels of tuberculosis infection in health care facilities and suggest that exposure in the community is a significant factor in health care worker infections. In addition, the agency’s estimates relied on assumptions about the progression of tuberculosis from infection to active disease and from disease to death that are widely used but inconsistent with available data and are unlikely to fit employed workers with reasonably good access to health care. PUBLIC POLICY AND THE CHANGING EPIDEMIOLOGY OF TUBERCULOSIS Unlike typical workplace health problems such as those involving exposure to hazardous chemicals or dust, the likelihood of occupational

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Tuberculosis in the Workplace exposure to tuberculosis has a close connection to the risk of tuberculosis in the surrounding community. Those responsible for occupational health programs cooperate with those responsible for public health programs to track and prevent the transmission of tuberculosis. The committee draws a parallel between the circumstances facing workplace tuberculosis control programs and the circumstances described in the recent IOM report Ending Neglect: The Elimination of Tuberculosis in the United States (IOM, [2000]). That report attributed the resurgence in tuberculosis in the mid-1980s to the complacency that followed the introduction and spread of effective treatment beginning around 1950. Complacency led to neglect of basic public health measures including surveillance, contact tracing, outbreak investigations, and case management services to ensure that individuals completed treatments for latent infection and active disease. This neglect helped set the stage for the resurgence of tuberculosis when new circumstances emerged—including the HIV/AIDS epidemic, the increase in multidrug-resistant disease (largely due to incomplete treatment), and expanded immigration from regions of the world with high rates of tuberculosis. For health care facilities, prisons, and other organizations that serve people at high risk of tuberculosis, a similar pattern of workplace complacency in the late 1980s and early 1990s—combined with an increasing incidence of tuberculosis in the community—contributed to workplace outbreaks of tuberculosis. Surveys, investigations of outbreaks, and facility inspections all pointed to institutional lapses in tuberculosis control measures including inattention to the signs and symptoms of infectious tuberculosis, delays in the initiation of appropriate evaluation and treatment, and improper ventilation of isolation rooms. Just as community neglect interacted with workplace neglect to set the stage for workplace outbreaks of tuberculosis, it now appears that community control measures have interacted with workplace control measures to help end outbreaks of tuberculosis and reduce the potential for new ones. For example, increased government funding and public health efforts to ensure that individuals complete their treatments for active tuberculosis can be credited with reducing the number and proportion of infectious people—including those with multidrug-resistant disease—who appear in hospitals and other workplaces. At the same time, the implementation of tuberculosis control measures as recommended by CDC has almost certainly reduced the rate of transmission of drug-sensitive and multidrug-resistant tuberculosis in hospitals and in the broader community into which patients are discharged. The challenge now is for policymakers, managers, and health professionals to understand and adapt to the decreasing incidence of tuberculosis without re-creating the conditions that would make institutions and workers vulnerable to new and possibly more deadly outbreaks of the

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Tuberculosis in the Workplace disease. If tuberculosis case rates continue to decline, the maintenance of expertise and vigilance will not be easy. Ending Neglect laid out a strategy for maintaining long-term vigilance and moving toward the elimination of tuberculosis in the United States. This strategy stresses (1) better methods for identifying people with recently acquired tuberculosis infection, (2) stronger efforts to effectively treat people who could benefit from treatment of infection, (3) research to develop effective vaccines, (4) more active product development initiatives focused on diagnostic and treatment technologies, and (5) research to tackle the problem of patient and provider failure to follow treatment recommendations. If implemented, many of the recommendations from that IOM report—especially those related to better diagnostic tests and treatments for latent infection—would benefit workplace as well as community-based tuberculosis control programs. Ending Neglect also calls for the United States to increase its support for global tuberculosis control. With more than 40 percent of the tuberculosis cases in the United States (and in health care facilities in particular) involving people born in other countries, policymakers and public health authorities cannot ignore the international aspect of tuberculosis. In summary, just as the risk of tuberculosis in the workplace is linked to the risk of tuberculosis in the surrounding community, the risk in American communities is affected by that elsewhere in the world and by the migration of infected persons within and across U.S. borders. Effective tuberculosis control measures in the workplace are one element of much broader national and international strategies to prevent and eventually eliminate the disease. The resurgence of the disease in the United States in the mid-1980s and early 1990s and the rise of multidrug-resistant disease demonstrate that tuberculosis remains a threat that public health programs cannot afford to ignore.