Reason for posting: Tuberculo-

sis poses an enormous health burden worldwide, and tubercu-lin skin tests, which are simple and sensitive, are widely used to screen for the infection. Local hypersensitivity reactions are expected, intended and, in fact, an expression of what the test is supposed to measure. Recently, however, Health Canada has warned of serious allergic reac-tions, including anaphylaxis, in some recipients.1 The test: Mantoux tuberculin skin tests are often administered to those who may be exposed to tuberculosis infection, including people from endemic areas, health care workers and others who work in long-term care fa-cilities, group homes, drug treat-ment centres, prisons and shel-ters for the homeless. People who are immunosuppressed (e.g., patients with HIV infection, dia-betes or renal failure) are also of-ten tested, because they are at greater risk of developing the ac-tive form of tuberculosis. To perform the test, 5 tuber-culin units of purified protein derivative (PPD) of Mycobacteri-um tuberculosis is injected intra-dermally, often in the volar skin of the forearm. A delayed hyper-sensitivity reaction usually starts within 24 hours, reaching its peak between 48 and 72 hours, which is when the test result is read. Characteristically, a circu-lar area of erythema occurs around a more central area of in-duration. (Guidelines for inter-preting the test result are cov-ered elsewhere.2) In 1%–2 % of positive test results, blistering or even local necrosis may occur, but this is usually self-limited.2 Local reactions such as regional lymphangitis and adenitis may also occur on rare occasions. Health Canada now reports systemic hypersensitivity reac-tions occurring in some people after the test, including anaphyl-axis, urticaria, angio- and other edema, and throat swelling. Al-though the Health Canada advi-sory reports few clinical details, these reactions appear to have occurred in at least some pa-tients not previously exposed to the test. Although such adverse events are probably underreported once a product is marketed, these ser-ious reactions seem to occur at a rate of about 1 per million doses dispensed. This rate is similar to anaphylaxis rates typically re-ported for vaccines (1.1–3.1 per million distributed doses).3 In the past 12 years, 26 serious re-actions were reported world-

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.