A caveat: Be wary of tuberculosis comeback

The bottom line is that some risk remains’

Though finalization of the 1997 proposed tuberculosis standard by the Occupational Safety and Health Administration (OSHA) may be delayed indefinitely or abandoned outright, experts are warning hospitals and other institutions not to slip into complacency and assume TB poses no threat to health care workers.

Though TB infection controls may not be regulated, compliance with voluntary guidelines should continue to keep the ancient disease at bay. The history of TB has been described as the "U-shaped curve of concern," meaning that as funding and prevention efforts wane, the disease begins rising again. Such was the case in the United States in the 1980s and early 1990s, when calls began for an OSHA standard to protect health care workers.

"The bottom line is that some risk remains, and that while on average, it is no greater than the community risk where they live, it is [greater] for certain areas," says Walter Hierholzer, MD, chairman of the Institute of Medicine (IOM) panel that reviewed the proposed TB standard.

"It certainly is [greater] if you don’t apply infection control standards," he points out. "The report doesn’t say that you can forget about infection control because there isn’t any risk to health care workers."

According to the IOM panel’s report, there does appear to be a risk of TB infection to health care workers in the workplace, and in some job circumstances, that risk may be greater than that encountered in the community. Procedures that generate aerosols are particularly hazardous to exposed employees, the IOM panel warned.

"I would be quite worried about risk and be very careful about infection control if I worked in respiratory therapy, even in areas where TB is not prominent, like the Midwest," Hierholzer says. "Second, the risk varies geographically, as it does in the general population. Certainly, if I worked in New York City, Los Angeles, or San Francisco,
I would still be very careful, try to identify all cases, and have a good control program with both engineering and administrative controls."

According to the IOM report, those who reported their occupation as health care workers within the preceding 24 months accounted for approximately 2.6% of TB cases nationwide in 1999, down from 3% in 1998. During the period from 1994 to 1998, six states — California, Florida, Illinois, New Jersey, New York, and Texas — accounted for 57% of the cases of TB among health care workers and about the same percentage of all TB cases. The six states account for just under 40% of the U.S. population.

Also, from 1994 to 1998, there were significantly higher rates of drug-resistant disease for health care workers (3.2% of cases) than for other workers (1.5% of cases). For the two most recent years, the difference in rates for the two groups was not statistically significant.

Studies suggest recent occupational TB infection risks of about 0.5% to 1% per year for hospitals in low-TB-incidence areas and about 1% to 5% a year for hospitals in high-incidence areas. Those risks fall steadily as influenced by implementation of infection control measures. In addition, the report clarified that attack rates among tuberculin reactors are substantially lower than the oft-stated 10%. Studies suggest a 3% to 5% rate may be more accurate, the report states.

"We had newer data than OSHA had," Hierholzer says. "The newer data would seem to suggest that some of the levels of risk that OSHA originally proposed in 1997 were higher than we saw now. Whether that will continue is unknown. There still is some risk there, but it is very geographical and related to community risk. It is very variable by worker."

The committee also determined that respiratory protection is important when dealing with TB cases, he adds. "There were some suggestions a while back that if one had very good engineering and administrative controls, then one would not need to wear a mask," he says. "We think that is imprudent and probably dangerous."