Bulletin of the World Health Organization | January 2007, 85 (1) Editorials Leprosy: what is being “eliminated”?

Leprosy is a well known but poorly understood disease; even its sources and modes of infection transmission are still contentious issues. The World Health Organization has made important contributions to leprosy research and control through inclusion of leprosy in the multi-agency Special Programme for Research and Training in Tropical Diseases (TDR) and by leading a global leprosy elimination initiative. In 1991 the World Health As-sembly (WHA) passed a resolution to “eliminate leprosy as a public health problem ” by the year 2000. The implications of this resolution have dominated discussion and activity in the leprosy community in the past 15 years. A footnote to the WHA resolution explained that elimination was to be defined in this context as a reduction in prevalence below 1 per 10 000. This is important. Prevalence at any point in time (e.g. 31 December) is a function of duration, as well as of incidence, and the primary strategy of the initiative has been to reduce preva-lence by reducing treatment duration through the institution of short-course multiple-drug regimens. It was also hoped that use of these shorter-term and more-effective drug regimens would reduce infection transmission, and thus effectively reduce incidence of infec-tion and ultimately of disease. The programme has had a massive effect on reported prevalence. Accord-ing to data submitted to WHO — the global figures are presented annually in the Weekly Epidemiological Record (WER), most recently in August 2006 — the elimination target was reached globally (using the total human popu-lation as a denominator) in 2000, and by the end of 2005 all but six countries reported year-end prevalence below 1 per 10 000. That much is a success. However, if one looks closely at the published data, it is not clear what has actually happened