The THELEP controlled clinical trials in lepromatous leprosy

Clinical trials of multidrug therapy (MDT) in lepromatous leprosy were carried out over a period of two decades in Mali and India. On completion of the trials, a number of questions had been answered and the world of leprosy was very much changed. At the time the trials began, there were two major concerns: the resistance of the leprosy bacillus to the drug dapsone, which up to that time had been used alone, and association of this resistance to relapse of the disease; in the lepromatous patient (with an inadequate immune system), the persistence of some leprosy organisms which, despite being fully susceptible to the drugs used, could survive long periods of treatment and were thought likely to cause relapse. More effective and shorter treatment than the indefinitely long regimen needed with dapsone was clearly necessary if patients and health services were to comply with it. By the end of the trials it had become evident that resistance to dapsone was increasing considerably, emphasizing the need for MDT, but also it was evident that persistent organisms did not constitute much of a risk for relapse. MDT had become standard practice and, as a consequence, the prevalence of leprosy was decreasing dramatically. Due to the rapidly changing picture, the series of papers published during the course of the trials were not in a logical order. This volume was therefore compiled to present the papers and results of the trials more coherently and concisely. The trials were carried out under the TDR Scientific Working Group on Chemotherapy of Leprosy (THELEP) in close collaboration with WHO’s leprosy programme.