[Leprosy--current aspects of a disease from biblical times]

95% of individuals who come in contact with M. leprae do not develop an overt disease. It begins as an indeterminate form that may undergo spontaneous cure or may progress to different forms of leprosy (TT, BT, unstable form of BB, BL, or LL). The clinical form of the disease correlates with the T cell mediated immune response rather than to the direct damage caused by the bacilli. The lack of cellular immunity in lepromatous patients relates specifically to M. leprae. Current aspects of etiology, transmission, epidemiology, classification, clinical features, immunopathology, chemotherapy, treatment of reactions, immunotherapy and vaccination are elucidated and discussed.