New recommendations for contact tracing in tuberculosis

In 2007, the German Central Committee against Tuberculosis (DZK) published recommendations for contact tracing that introduced the new interferon gamma release assays (IGRAs). Meanwhile, substantial progress has been made in documenting the utility of IGRAs. Because IGRAs are usually superior to the tuberculin skin test (TST) in detecting latent TB infection (LTBI) with respect to sensitivity and specificity in adult contact populations that are at least partially BCG vaccinated, it is now recommended that instead of two-step testing only IGRAs be used.[nl]As the literature does not yet provide sufficient data on the accuracy of IGRAs in children younger than 5 years, the TST remains the method of choice in that age group. To date, also, no clear body of data exists to substantiate better performance for IGRAs than for the TST in older children, thus in this age group using of either test is recommended. The new recommendations also underscore the importance of a diligent preselection of close contacts in order to achieve a high probability that positive test results represent recent infection and to thus increase the benefit of chemopreventive treatment for those identified as requiring it. In a third point of update, it is noted that re-testing of contacts individuals found positive for LTBI may produce a considerable number of false-negative results and should thus be avoided in case of documented exposure.