A pattern for the pathogenesis of early leprosy infection starts to emerge.
Although it may at times look as though new technologies are utilized to revisit old ideas, much can be expected from these studies in the years to come, and could have significant implications to face possible setbacks and make room for the need to adjust the post-elimination control measures.
As a parenthesis, though this is perhaps not the right place, a word should be said on the importance of the M. leprae genome sequencing project, now close to its completion. It will in some way substitute for this long sought for and never attained goal of its cultivation in vitro. A number of epidemiological as well as more fundamental research undreamed of until recently, will become possible. Matches and mismatches between the genetic sequences of M. leprae and M.tuberculosis will offer new insights on the respective distastes or gustos of these microorganisms, as well as help in designing drugs specially targeted on specific metabolic pathways. It could also lead to the engineering of a synthetic vaccine.
It is amazing to think that, while for a long time attempts were made, often with little success, to combine the field activities against leprosy and tuberculosis, the two bacilli will now be companions in the laboratory together with a panoply of other mycobacteria.
Having considered these current worries, and turning resolutely to the future, what is to be done? It is obvious that a prevalence of I per 10,000 as the target of elimination, and the Year 2000 as the deadline, are not goals per se. They are nothing but milestones on the way to having the "final word" against leprosy. I deliberately use the term "final word" because it is vague enough and precludes a firm definition. According to the epidemiological context of each country and its socio-economic conditions, the aim could be make leprosy a rare disease, ultimately eradicating it.
It should be clear for everybody that elimination programs should be continued after the Year 2000 to achieve what should have been achieved by then. Conversely, it would be absurd to wait for the millennium to initiate, develop or expand needed activities not directly related to the program.
The question is： can we go along with the same objectives, the same strategy, the same methods, once the prevalence goals of elimination have been achieved. The answer, I think is clearly "no". The program of elimination of leprosy as a public health problem was and still is linked to the tremendous opportunity offered by chemotherapy, which has allowed us to strike a full fledge blow knocking out M. leprae inside the human reservoir. But there is more to leprosy than MDT, and more to the fight against leprosy than mere decimal digits.
