Eliminating Leprosy in India--Is it a Dream?

In recent years there have been considerable discussions on the current leprosy situation in India and the status of the country's attempts to eliminate or eradicate the disease. In this connection it is very important to analyze the background and various developments relevant to leprosy elimination in India.

Leprosy research and elimination.

The contribution of leprosy research to the progress being made toward elimination of leprosy has been critical. A major development in the promotion of leprosy research during the last 25 years has been the initiative taken by the WHO Special Programme for Research and Training in Tropical Diseases (TDR) through two of its scientific working groups, one on the immunology of leprosy (IMMLEP) and the other on the chemotherapy of leprosy (THELEP), which were set up in 1974 and 1976, respectively. IMMLEP and THELEP have greatly facilitated inputs from scientists not usually active in leprosy research. The coordinated efforts of IMMLEP and THELEP also facilitated goal-oriented research toward high-priority target areas such as an anti-leprosy vaccine and newer and better drug-combinations for the treatment of leprosy. Whereas the prospects for a leprosy vaccine appeared very promising in the early years, the first vaccine produced did not meet expectations for several reasons. Moreover, the possibility of using a vaccine in leprosy is not bright, because of both the technical problems as well as the reduced relevance of a vaccine at a time when leprosy is becoming less and less common. On the other hand, the modest expectations for newer and better drug combinations led to multi-drug therapy (MDT) for the control of leprosy. It is the introduction of MDT that is credited with the current global reduction of leprosy and the progress thus far made toward eliminating the disease as a public health problem. Nevertheless, many areas in leprosy, such as nerve damage, remain that require major research inputs in the future.

Prophylaxis--scope and limitations.

Attempts to prevent leprosy by one or another prophylactic method began with the use of dapsone as a chemoprophylaxis. Following early, small-scale studies, which were promising, large-scale studies with dapsone and acedapsone, both among contacts and in the general population, demonstrated that it is possible to prevent the occurrence of leprosy to a modest extent. With regard to immunoprophylaxis, BCG had long been considered a possibility, particularly in view of its potential to convert the skin test reaction to lepromin. Over the years, major, large-scale field trials of BCG had been carried out in Uganda, Burma, Papua New Guinea and India. All of the studies demonstrated that BCG was capable of preventing leprosy. However, protective efficacy varied from around 20% to greater than 80%. Killed Mycobacterium leprae mixed with BCG has also given varying results. Other vaccines based on cultivable mycobacteria have also been tried, and at least one of them appears promising. An approach to prophylaxis must take into account (a) the level of risk addressed and the perception of risk by the community; (b) the level of efficacy of the method of prophylaxis; (c) the possibility of easily identifying high-risk groups; (d) the operational feasibility; and (e) the focus of the prophylaxis, whether the individual or the community, or both. However, in view of the enormous progress being made towards elimination of leprosy by the widespread application of MDT, prophylaxis is becoming less and less relevant and less and less cost-effective, except in very special situations.

Eliminating leprosy as a public health problem--is the optimism justified?

Systematic use of multidrug therapy has proved to be so effective that leprosy can be eliminated as a public health problem by the end of the century. However, because of the long incubation period of this disease, together with the time-lag in case detection, the factors involved in achieving and sustaining its elimination have to be very carefully defined.