[HAS evaluation: interferon gamma detection test for the diagnosis of tuberculous infections]

Infection with Mycobacterium tuberculosis is limited by the host immune defenses in most individuals, and the infection remains latent. In 10% of patients, the latent tuberculosis infection can be reactivated and cause active disease. The tuberculin skin test is the established screening method for diagnosing latent tuberculosis infection, but it poses many problems such as cross reactivity due to prior BCG vaccination. A new type of in vitro Tcell based assay, for the detection of tuberculosis infection, was recently developed. This interferon gamma (IFNgamma) blood assay is based on the measure of IFNgamma production by previously sensitized lymphocytes in response to the M. tuberculosis specific proteins. The French National Authority for Health assessed the two commercial IFNgamma assays. Assessment was based on the critical review of scientific literature and the opinion of experts in the field.The diagnostic tool of IFNgamma detection test was considered indicates in four situations: diagnosis of latent tuberculosis infection in adults; before health care worker recruitment; diagnosis of extrapulmonary form of tuberculosis disease; before starting anti-TNFalpha treatment. This report states that IFNgamma assays may be used instead of a tuberculin skin test in these four situations.