and white male health and nursing aides, orderlies, and attendants. Of the other occupational subgroups identified, six were classified as having the potential for substantial exposure to silica and two were associated with low socioeconomic status.

Infection with M. tuberculosis In 1992, concerned about a number of hospital outbreaks of tuberculosis, CDC sent questionnaires all 632 public hospitals and a 20 percent sample (444 institutions) of private hospitals with 100 beds or more that were listed in the American Hospital Association database (Manangan et al., 1998). About 70 percent for each group responded (726 institutions in total). Ninety-six of 716 hospitals (13 percent) reported transmission of M. tuberculosis to health care workers. In 1996, CDC randomly selected and resurveyed half of the 272 hospitals that had reported six or more admissions of tuberculosis patients in the 1992 survey (Manangan et al., 1998, 2000). Seventy-five percent (103 facilities) responded. In that survey of higher-risk facilities, 7 percent of 103 respondents reported transmission of M. tuberculosis to workers.

In 1995, CDC began a demonstration project to develop better estimates of workplace-related skin test conversions among health care workers and to test software to support more systematic collection and analysis of skin test data (McCray, 1999a,b). The project recruited 32 participating facilities from nine jurisdictions including both high-prevalence areas (New York City and San Francisco) and low prevalence areas (Oregon and Colorado). Using data collected prospectively from the demonstration project sites, CDC analysts reported an overall tuberculin skin test conversion rate of 5.9 per 1,000 health care workers. Rates differed little among the types of participating organizations (nine hospitals, seven correctional facilities, five health departments, two nursing homes, and seven other types of facilities). After adjusting for race, foreign birth, New York City residence, and household exposure, analysts found no statistically significant associations between skin test conversions and the occupational categories used (administrative/clerical, nurse, outreach worker, physician/physician’s assistant, and other). Data were not collected on the extent of workers’ contact with patients or on their work location within facilities (e.g., medical ward). More than 20 percent of those participating had either a positive skin test history or a positive test result at the baseline.

Additional, older data analyzed in Appendix C by Daniel are mixed. He concludes that health care workers are at risk in the workplace of being infected with tuberculosis but that the risk has been declining in recent years and now approaches community levels. Where modern infection control measures have been implemented, occupational risk approaches the level of risk in the communities in which workers reside.

Overall, data for the mid-1990s do not show that health care workers as a group are at higher risk of active tuberculosis than other employed



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