Elimination of Leprosy as a public health problem by 2000 AD: an epidemiological perspective

Introduction: Leprosy is caused by Mycobacterium leprae and manifests as damage to the skin and peripheral nerves. The disease is dreaded because it causes deformities, blindness and disfigurement. Worldwide, 2 million people are estimated to be disabled by leprosy. Multidrug therapy is highly effective in curing leprosy, but treating the nerve damage is much more difficult. The World Health Assembly targeted to eliminate leprosy as a public health problem from the world by 2000. The objective of the review was to assess the successes of the leprosy elimination strategy, elimination hurdles and the way forward for leprosy eradication. Methods: A structured search was used to identify publications on the elimination strategy. The keywords used were leprosy, elimination and 2000. To identify potential publications, we included papers on leprosy elimination monitoring, special action projects for the elimination of leprosy, modified leprosy elimination campaigns, and the Global Alliance to eliminate leprosy from the following principal data bases: Cochrane data base of systematic reviews, PubMed, Medline, EMBASE, and the Leprosy data base. We also scanned reference lists for important citations. Key leprosy journals including WHO publications were also reviewed. Results: The search identified 63 journal publications on leprosy-related terms that included a form of elimination of which 19 comprehensively tackled the keywords including a book on leprosy elimination. In 1991, the 44th World Health Assembly called for the elimination of leprosy as a public health problem in the world by 2000. Elimination was defined as less than one case of leprosy per 10000-population. Elimination has been made possible by a confluence of several orders of opportunities: the scientific (the natural history of leprosy at the present state of knowledge), technological (multi-drug therapy and the blister pack); political (commitment of governments) and financial (support from NGOs for example the Nippon Foundation that supplies free multi-drug therapy) opportunities. Elimination created the unrealistic expectation that the leprosy problem could be solved by 2000. First, the elimination goal was not feasible in several areas which had high incidence of leprosy. Even if elimination was to be attained, significant numbers of new cases of leprosy would continue to occur and many people with physical imperfections, severe psychological, economic and social problems caused by leprosy would need continuous assistance. Extra-human reservoirs of Mycobacterium leprae, the relationship between leprosy and poverty, prevention of disabilities, lack of a reliable laboratory test to detect subclinical infection and a vaccine are also challenging issues. Conclusion: The evidence base available to inform on leprosy elimination is highly positive with the availability of multi-drug therapy blister packs. There are concerns that leprosy was not the right disease to be targeted for elimination as there are no reliable diagnostic tests to detect subclinical infection including the lack of a vaccine, extra-human reservoirs (monkeys and armadillos), increase in the burden of child cases, no good epidemiological indicator as prevalence instead of incidence is used to measure elimination. Multi-drug therapy treats leprosy very well but there is no proof that it concurrently interrupts transmission. The high social stigma, prevention of disabilities, and the relationship between leprosy and poverty are still major concerns.