Volume 22-17
1 September 1996

[Table of Contents]

International Notes

PROGRESS TOWARDS THE ELIMINATION OF LEPROSY AS A PUBLIC HEALTH PROBLEM

Introduction

For the first time since global statistics on leprosy were collected, the number of patients registered for treatment in the world has fallen below 1 million. More importantly, almost all registered cases now have access to multidrug therapy (MDT). Improvements in the coverage of leprosy elimination programs have led, in turn, to improved case detection and also to a steady increase in coverage with MDT from 76% to 91% in the last year.Thus, the large backlog of leprosy patients waiting for appropriate treatment has been reduced significantly and the gap between the number of estimated cases and the number of cases registered for treatment is steadily decreasing. However, it should be recognized that, in some countries, substantial numbers of patients do not have easy access to diagnosis and treatment; this could hamper the elimination of leprosy at the national and subnational levels in a number of highly endemic countries.

The prevalence of leprosy worldwide was reduced by 28% between 1995 and 1996, compared with 27% between 1994 and 1995. These reductions can be explained by the conjunction of the following factors: wider implementation of MDT; fixed duration of treatment; and updating of the leprosy registers.

Estimated prevalence

In the absence of precise tools to measure infection, and considering that the diagnosis of leprosy is mainly clinical, it is somewhat difficult to estimate the true prevalence of leprosy in the world. Estimates presented in this report are based on information provided by national program managers and are derived from registered figures, taking into account health service coverage and MDT implementation. Despite limitations, global estimates are believed to be accurate enough for priority setting and for planning intensified activities at the national and subnational levels.

Estimates for 1996 indicate that there are about 1.3 million cases of leprosy in the world. It is estimated, however, that over 330,000 leprosy cases have yet to be detected, about 50% of them living in Asia. The widest gaps between registered and estimated cases are reported particularly in countries with poor service coverage.

Table 1 Registered cases of leprosy and coverage with multidrug therapy (MDT), by WHO region, 1996

Registered prevalence

There was a significant reduction in the number of registered cases worldwide (-28%) from 1995 (1,286,932 cases) to 1996 (926,259 cases); this reduction has been observed in all endemic countries and regions, with the exception of Guinea, Sudan and Madagascar. Over the past 10 years, the leprosy problem was reduced by 83% worldwide, although the reduction in the American Region was only 60%.

The global prevalence rate of registered cases decreased from 2.3 to 1.7 per 10,000 population between 1995 and 1996. However, in the top 16 endemic countries, the prevalence rate is still 4.5 per 10,000, i.e., 5 times higher than the elimination target (below 1 case per 10,000 population).

Detection of leprosy cases

Since 1993, the global detection of leprosy cases has declined, although it is difficult to interpret this trend. Declines have been observed in all WHO Regions, with the exception of the Americas.

Annual detection rates are still very high in some countries, or in some regions within countries. The extent to which this reflects the high level of disease transmission is not clear, but these countries or regions will have significant difficulty in reaching the elimination target on time and will need special attention.Achievements with MDT By the beginning of 1996, more than 90% of registered leprosy patients were being treated with MDT and, so far, about 8 million persons have been cured through this treatment. During 1995, more than 1.5 million cases, old and new, received MDT. Table 1 gives details of MDT coverage for registered patients at the global and regional levels.

Clearly, this illustrates the important progress made in a span of 2 years, i.e. an MDT coverage of 91% in 1996 compared with 55% in 1994. The increase in MDT coverage is a result of the efficacy and acceptability of MDT which is fully standardized and of fixed duration. The number of treatment failures or relapses remains very low and drug resistance to MDT has never been reported. The supply of adequate quantities of drugs at the peripheral level, together with the fact that treatment is free of charge, have contributed to optimal compliance.

Progress towards the elimination of leprosy

Leprosy remains a public health problem in 60 countries or areas, but 16 countries account for 90% of the leprosy problem in the world.

Conclusion

The strategy for eliminating leprosy as a public health problem has already had a significant impact: the dramatic and constant reduction in morbidity; increased priority to leprosy control activities in the most endemic countries; free supply of MDT drugs through WHO to the countries in need; and focused attention on difficult-to-reach populations. These are some of the direct benefits of this strategy, although these encouraging achievements should not undermine the fact that considerable challenges still remain before the elimination of leprosy in some parts of the world can be attained.

Source: WHO Weekly Epidemiological Record, Vol 71, No 20, 1996.

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