sols likely to be present in isolation rooms of newly diagnosed patients” (p. 754). For workers involved in cough-inducing procedures for infectious patients, more sophisticated respirators may be needed to protect workers adequately. The benefit to workers of using respirators is probably minimal if patients are being properly treated in properly ventilated isolation rooms.

Another modeling exercise reported by Barnhart and colleagues (1997) came to generally similar conclusions but placed greater emphasis on cumulative risk over a worker’s lifetime. The authors concluded that higher-level respiratory protection (more than a disposable mask respirator) was reasonable for workers in higher-risk situations (e.g., those performing bronchoscopies or those treating highly infectious patients or patients with multidrug-resistant disease).

A Chicago study suggests the ineffectiveness of personal respirators when adequate administrative and engineering controls are lacking. Kenyon and colleagues (1997) reported an outbreak of multidrug-resistant tuberculosis in a facility that provided and fit tested workers with high-efficiency particulate respirators but that had no isolation rooms that met CDC criteria. Three of the 11 previously skin test-negative workers whose tuberculin skin test result converted to positivity (including a ward secretary with no patient care responsibilities) had no contact with the source case patients. The authors conclude that a respiratory protection program alone cannot protect all workers. In the absence of appropriate isolation rooms, air that escapes from rooms housing infectious patients can infect those outside the room. Delays in recognizing and treating infectious patients also contributed to the outbreak. (Appendix F presents additional background on personal respiratory protection as a tuberculosis control measure.)

COMMITTEE CONCLUSIONS

When the resurgence of tuberculosis began in the mid-1980s in the United States, communities and workplaces were generally not prepared. After years of effective treatment and declining tuberculosis case rates, tuberculosis control measures—including those recommended by CDC in 1983—were not priorities for either public or occupational health programs. The epidemic of HIV infection and AIDS and public health and medical responses to the epidemic were still emerging issues, and the interaction of that epidemic with tuberculosis was not well documented or understood. Similarly, the threat of multidrug-resistant disease was not yet clearly appreciated.

Much has happened in the past 15 years. Certainly, the epidemiology of tuberculosis has changed, with case rates again in decline since 1993. Virtually all states have shown decline, although relatively high rates of



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