Healthcare workers represent the largest group of TB-exposed workers, and in the early years of TB recordkeeping, they were more likely than other workers to develop TB. As the Society for Healthcare Epidemiologists of America (SHEA) noted, more recent data indicate that healthcare workers "represent a small proportion of all cases and are not disproportionately represented in the TB caseload compared to their presence in the workforce". IOM reported that for 1998, although healthcare workers accounted for 9% of the working population of the U.S., these workers accounted for only 8% of TB cases among the working population, which does not appear consistent with these workers being at much higher risk of infection than the rest of the population. Moreover, from 1994 to 1998, the TB rate for health care workers declined almost 20%, from 5.6 to 4.6 per 100,000 population, while the rate for other workers remained steady at 5.2 per 100,000.
Because TB rates among healthcare workers vary demographically in a manner similar to rates among the general population, and because it is very difficult to determine whether any individual case was transmitted occupationally, many participants believed that much of the risk to these workers likely arises outside of work. For example, the Infectious Disease Society of America pointed to data "suggest[ing] that community exposure was responsible for most conversions even at a hospital which cares for a large number of TB patients." IOM pointed out that foreign-born workers account for a very high percentage of TB cases in healthcare workers. Many of these workers are from countries such as India and the Philippines, which have very high TB rates.
