In this paper we describe identification and characterization of Mycobacterium leprae ESAT-6 (L-ESAT-6), the homologue of M. tuberculosis ESAT-6 (T-ESAT-6). T-ESAT-6 is expressed by all pathogenic strains belonging to the M. tuberculosis complex but is absent from virtually all other mycobacterial species, and it is a promising antigen for immunodiagnosis of tuberculosis (TB). Therefore, we analyzed whether L-ESAT-6 is a similarly powerful tool for the study of leprosy by examining T-cell responses against L-ESAT-6 in leprosy patients, TB patients, and exposed or nonexposed healthy controls from areas where leprosy and TB are endemic and areas where they are not endemic. L-ESAT-6 was recognized by T cells from leprosy patients, TB patients, individuals who had contact with TB patients, and healthy individuals from an area where TB and leprosy are endemic but not by T cells from individuals who were not exposed to M. tuberculosis and M. leprae. Moreover, leprosy patients who were not responsive to M. leprae failed to respond to L-ESAT-6. A very similar pattern was obtained with T-ESAT-6. These results show that L-ESAT-6 is a potent M. leprae antigen that stimulates T-celldependent gamma interferon production in a large proportion of individuals exposed to M. leprae. Moreover, our results suggest that there is significant cross-reactivity between T-ESAT-6 and L-ESAT-6, which has implications for the use of ESAT-6 as tool for diagnosis of leprosy and TB in areas where both diseases are endemic.Tuberculosis (TB) and leprosy are major public health problems in the developing world. One-third of the world's population is infected with Mycobacterium tuberculosis, and around 2 million individuals suffer from leprosy (9). Many studies have shown that early culture filtrate proteins of M. tuberculosis can be dominant target antigens for CD4 ϩ Th1 cells both in animal models of TB (1, 2, 5, 12, 13) and in humans. One of these secreted antigens, called T-ESAT-6, is a 10-kDa protein which is present in M. tuberculosis and virulent M. bovis but not in M. bovis BCG, and this protein could not be detected in M. leprae, M. avium, M. scrofulaceum, M. intracellulare, M. fortuitum, and M. xenopi (3, 11). Indeed, when the T-ESAT-6 protein was used, TB-infected cattle could be distinguished from cattle sensitized by environmental mycobacteria (15), and in humans T-ESAT-6 and T-ESAT-6-derived peptides were shown to be very efficiently and specifically recognized by individuals exposed to M. tuberculosis (4,14,16,21). The gene for ESAT-6 (Rv3875) is in a region of the M. tuberculosis genome, designated RD1, that is indeed absent from M. bovis BCG and most nontuberculous mycobacteria (NTM).The existing diagnostic skin test reagents for leprosy, lepromin and leprosin, are prepared from whole autoclaved M. leprae and from the soluble fraction of M. leprae, respectively, and contain many mycobacterial antigens shared with other species (20). A more specific skin test reagent for leprosy would be a highly desirable diagnostic tool. Becaus...

Background Leprosy or Hansen's disease is a chronic infection caused by Mycobacterium leprae (M. leprae) or Mycobacterium lepromatosis (M. lepromatosis). In Europe, most of the leprosy cases are imported. However, occasionally a case is diagnosed in one of the old endemic foci. Leprosy is often not suspected because it is no longer emphasized in the medical curricula. Attention shifted from leprosy to tuberculosis and human immunodeficiency virus infections in the late 20th century, whereby the WHO leprosy programme was toned down in the conviction that leprosy was all but eliminated. The result of unawareness is a harmful doctor's delay. Material and methods This paper focusses on clinical diagnosis, complications and treatment based on literature and experience. Results It mentions the value of laboratory tests in classification, follow‐up and detection of relapses. It discusses the etiopathology. Conclusion This is a position statement.

Mycobacterium tuberculosis culture filtrate protein-10 (CFP-10) (Rv3874) is considered a promising antigen for the immunodiagnosis of tuberculosis (TB) together with early secreted antigens of M. tuberculosis (ESAT-6). Both ESAT-6 and CFP-10 are encoded by the RD1 region that is deleted from all tested M. bovis bacille Calmette-Guérin (BCG) strains but present in M. leprae, M. tuberculosis, M. bovis, M. kansasii, M. africanum and M. marinum. In this study, the homologue of CFP-10 in M. leprae (ML0050) is identified and characterized. Interferon-g production in response to this homologue by T cells from leprosy patients, TB patients and unexposed controls shows that CFP-10 of M. leprae is a potent antigen that crossreacts with CFP-10 of M. tuberculosis at the T-cell level. This crossreactivity has implications for the use of CFP-10 of these mycobacterial species as diagnostic tool in areas endemic for both the diseases.

Summary Objective  To review the history of the treatment of leprosy and leprosy reactions after World War II. Methods  Treatments based on experience and clinical evidence are compared with those advised by the WHO in their quest to eliminate leprosy by the year 2000, later extended to 2005. Results  Leprosy is not eliminated. Analyses of data on reaction treatment suggest that the treatment regimens for leprosy reactions as advised by the WHO may lead to more impairment among leprosy patients than the ‘old’ established regimes. Conclusion  WHO policies to eliminate leprosy may have jeopardized the proper treatment of leprosy for years to come.

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