Risk of relapse in leprosy. The Leprosy Unit, WHO.

Until the introduction by WHO of the standard regimens using multidrug therapy (MDT) for the treatment of leprosy, there was a general unwillingness to release patients from treatment. This was mainly due to the high risk of relapse after dapsone monotherapy. After almost a decade of MDT implementation and after releasing more than 4 million patients, it was necessary for WHO to review the risk of relapse following WHO-recommended MDT. The results of this study, carried out on more than 20,000 MB and 50,000 PB patients, revealed that the risk of relapse is very low, 0.77% for MB and 1.07% for PB, nine years after stopping MDT. In comparison to dapsone monotherapy, the risk is 10-times lower. Thus, over the last decade, MDT implementation has probably prevented close to half-a-million relapses.