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The New England Journal of MedicineNúmero: Volume 364(15), 14 April 2011, p 1441–1448Copyright: Copyright © 2011 Massachusetts Medical Society. All rights reserved.Tipo de publicación: [Clinical Practice]ISSN:0028-4793Registro: 00006024-201104140-00012[Clinical Practice] Latent Tuberculosis Infection in the United StatesHorsburgh, Robert C. Jr. M.D.; Rubin, Eric J. M.D., Ph.D.Información sobre el autorFrom the Boston University School of Public Health (C.R.H.) and the Harvard School of Public Health (E.J.R.) — both in Boston. Address reprint requests to Dr. Rubin at the Department of Immunology and InfectiousDiseases, Harvard School of Public Health, 200 Longwood Ave., Boston, MA 02115, or at firstname.lastname@example.org.An audio version of this article is available at NEJM.org.Dr. Rubin reports serving on an unpaid scientific advisory board for the Global Alliance for TB Drug Development and receiving consulting fees and travel reimbursement from Novartis; and Dr. Horsburgh, receiving consulting fees fromOtsuka Pharmaceutical. No other potential conflict of interest relevant to this article was reported.Disclosure forms provided by the authors are available with the full text of this article at NEJM.org. This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, whenthey exist. The article ends with the authors' clinical recommendations. |
A healthy 43-year-old woman presents for a pre-employment physical examination. She is originally from Ghana and came to the United States 18 months ago. Her employer, a hospital, requires a tuberculosis test. She reports having no known exposure to tuberculosis and no cough, fevers, or weight loss. Her physicalexamination is unremarkable. What screening test would you recommend, and how would you decide whether treatment is needed? |
The Clinical Problem |
More than 80% of cases of tuberculosis in the United States are the result of reactivated latent infection,12 and nearly all these cases could be prevented by the administration of a course of antibiotic treatment.1 Therefore, the U.S. Public HealthService recommends screening and treatment of persons at increased risk for latent tuberculosis as the critical strategy for elimination of tuberculosis in the United States.13 |
There is no way to directly detect the presence of latent Mycobacterium tuberculosis in an individual patient. Instead, the assessment of latent infection relies on measurement of host immune responses as a surrogate forthe presence of viable bacteria, an imperfect approach. Until recently, the only test for latent tuberculosis infection was the tuberculin skin test. Data from a representative survey of the U.S. population showed that 4.2% of persons who were screened with this test during 1999 and 2000 had latent tuberculosis infection.4 Although skin testing is sensitive, its specificity for predictingreactivation tuberculosis is poor; only about 5% of immunocompetent persons with a positive test will have progression from latent infection to disease in their lifetime.5 In addition, the antibiotic regimens that are currently recommended to prevent progression require 4 to 9 months of treatment,1 and the rate of adherence to prolonged courses of treatment is less than 50%.6 |
Recently, two newdiagnostic tests for latent tuberculosis infection have come on the market, QuantiFERON-TB Gold (QFT) (Cellestis) and the T-SPOT.TB test (Oxford Immunotec).7 Both tests are known as interferon-[gamma]-release assays (IGRAs) because they measure the release of interferon-[gamma] from cells in vitro. In addition, new regimens are being used or assessed for use in treating latent tuberculosis infection....