The use of biologic drugs for treating inflammatory joint diseases was approved at the end of last century. Several
cases of active lung and extra-pulmonary tuberculosis (TB) were reported at the beginning, and led to creating mandatory
screening for latent tuberculosis infection (LTBI) before initiating the treatment with them. The purified protein derivative
(PPD) test is the test of choice for diagnosing LTBI, but it has limited sensitivity and specificity, especially in the
tropical area. Furthermore, patients with autoimmune diseases have a low frequency of positive skin test compared to patients
who do not. Therefore, tests using Interferon Gamma Release Assays (IGRAs) have been carried out with a view to
their use in assisting to diagnose LTBI. This chapter places tuberculosis and latent tuberculosis infection (LTBI) in a
world context; recounts the origins of the two main tests for detecting LTBI and ant-TNF; evaluates their effectiveness as
seen today bearing in mind the incidence of active TB in any given country; and makes proposals for their optimum use
including when IGRAs might be used most appropriately.
Keywords: Latent tuberculosis infection, tuberculin skin test, PPD, anti-TNF, interferon gamma release assays, IGRAs.
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