Leprous neuropathies

Once a terrifying disease, leprosy today has a very hopeful prognosis, provided that it is diagnosed early and treated with modern multidrug chemotherapy, any immunological reactions being recognized quickly and controlled well to prevent (further) peripheral nerve damage after commencing treatment. The diagnosis should be considered in all patients who present with peripheral neuropathy and/or anaesthetic skin lesions who come from or have lived in the tropics and subtropics. Although M. leprae cannot yet be grown in vitro, it is readily grown in experimental animals. A complete gene library has been developed, much of the genome mapped and a number species-specific and common mycobacterial antigens identified. The intricacies of the host-parasite relationship, especially of cell-mediated immunity, and of the important immunological reactions of ENL and reversal reaction have been widely investigated. Modern MDT has caused a dramatic fall in prevalence, although the world annual case detection rate remains at around 600,000 new patients, many being at an early stage of the disease. WHO has launched a campaign to eliminate leprosy as a significant public health risk by the 2000 (with a prevalence of less than 1:10 000 population), which may well be achieved in some endemic countries. Leprosy will, however, remain an important cause of peripheral neuropathy for at least several more decades.