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By Gary Evans, Medical Writer
The Centers for Disease Control and Prevention is expected to issue new tuberculosis guidelines for healthcare workers that recommend blood tests over skin testing on hire, with retesting done only if there has been an exposure incident, the co-author of the document tells Hospital Employee Health.
The traditional practice of routine annual testing is not necessary in part because TB has been in steady decline in the U.S. and occupational transmission within hospitals has become a rare event.
“There is not literature to support that healthcare workers are at occupational risks of contracting TB from their patients anymore,” says co-author Wendy Thanassi, MD, MA, MRO, a professor at Stanford University and chief of Occupational Health Services at the Palo Alto VA Health Care System.
Other factors in the decline of TB as an occupational threat are the engineering controls and prevention measures that have become routine in many hospitals.
“Hospitals have done such a good job with environmental controls – negative pressure rooms, air filters, air circulation, and identifying patients and wearing masks early,” she says. “We have seen transmission decline because of these environmental controls.”
There are also new effective treatments of shorter duration for healthcare workers who have latent TB, which can remain dormant for years before activating.
“When we find people who are positive based on these blood tests, we can have them treated for their latent TB right away,” Thanassi says. “This obviates the need to test people every year because we are not finding that healthcare workers are converting year to year. The next testing that would be necessary for employees would be upon exposure to an active TB case.”
As this report was filed, the CDC had not issued the new guidelines. The current CDC guidelines say facilities can use the TB skin test or the blood test for healthcare workers at baseline and then retest thereafter depending on risk categories. Risk factors include the prevalence of TB in the patient population and the community. Hospitals at “medium” risk are currently recommended to test health care workers annually.
The new CDC guidelines are expected to drop the risk categories, essentially conflating them down to the “low” risk recommendation of retesting healthcare workers only if there has been a TB exposure incident, Thanassi says. In addition, the blood test is expected to be emphasized over the traditional skin tests, which often have to be done in a more labor-intensive “two-step” approach to ensure accuracy.
As opposed to skin tests, the blood tests do not “cross react” with the Bacillus Calmette–Guérin (BCG) vaccine, which may have been administered to healthcare workers from countries with higher prevalence of TB. This cross-reactivity can lead to a false positive TB test, so the CDC currently recommends use of the TB blood tests for workers who have been immunized with BCG. This TB vaccine is not routinely recommended in the U.S.
Although the blood tests have advantages, the new guidelines will likely state that those using traditional skin tests can continue to do so, as the CDC typically defers to local preferences rather than a one-size-fits-all approach in its recommendations.
For more on this story see the April 2019 issue of Hospital Employee Health.