Multidrug therapy (MDT)-the combination of three powerful anti-leprosy drugs-has now successfully cured more than 8.4 million sufferers since 1981, and the global strategy to eliminate the disease, which is based on MDT, is working extremely well. Consequently, the Seventh Expert Committee on Leprosy, which met at the World Health Organization (WHO) headquarters in Geneva from 26 May to 3 June, considered that, for a special class of early paucibacillary or PB leprosy-where patients have only one skin lesion-a single dose of three drugs in combination is sufficient to bring about a cure. The Committee also agreed on the possibility of shortening the treatment for the more severe form of the disease-multibacillary or MB leprosy-from 24 months to 12 months.

The United Nations Development Programme/World Bank/WHO Special Programme for Research and Training in Tropical Diseases initiated and supported a comprehensive multi-centre trial, which has shown that a combination of three drugs as a single dose-consisting of rifampicin (600 mg), ofloxacin (400 mg) and minocycline (100 mg)-is sufficient to cure patients with PB leprosy with single skin patches. The Committee considered that a single dose of this combination "is an acceptable and cost-effective alternative regimen for the treatment of single skin-lesion PB leprosy".

The implications of single-dose treatment for PB leprosy are considerable. Getting patients to comply with "doctor's orders" is a problem in any country. One visit by the patient to a health centre, where primary health care workers can supervise treatment, is clearly a much simpler matter than having to persuade each person to return for several treatments over a period of several months. There will also be welcome savings for cash-starved health services. For PB leprosy patients with more than one skin lesion, the standard treatment will continue to last for six months and consists of 600 mg rifampicin once a month and 100 mg dapsone daily.

Since 1994, the recommended standard treatment for MB leprosy has consisted of giving 24 months of treatment with rifampicin (600 mg once monthly), dapsone (100 mg daily) and clofazimine (300 mg once monthly and 50 mg daily). Now the Expert Committee has agreed that based on the information currently available, "it is possible that the duration of the current MDT regimen for MB leprosy could be further shortened to 12 months without increasing the risk of developing rifampicin-resistance".

Again, the implications in terms of reducing the workload on health professionals and reducing health service costs are appreciable, quite apart from the patient satisfaction that will result. A shorter duration also means that the patients will be less exposed to possible stigmatization at health centres.

Standard WHO/MDT is a "cocktail" of three drugs-dapsone, rifampicin and clofazimine-each of which has long proved lethal to the germ causing leprosy, Mycobacterium leprae. In combination, these drugs prevent the germ from developing drug resistance, particularly to rifampicin. More than 15 years of experience with MDT show that side-effects and relapses are extremely low, and there is no evidence of resistance developing to the combination of drugs. The treatment has proved itself both safe and efficacious.

With early detection of cases and increasing coverage of patients with MDT, the cases diagnosed each year are increasingly of the milder types. For various operational reasons, including the attitude of "playing safe", there has been a growing tendency to classify the milder PB patients as being the more serious MB patients, yet currently the true MB cases actually constitute a very small proportion of the total leprosy patients. The total of newly detected cases regarded as skin-smear positive-that is, where samples from the skin of suspects are shown by tests to have very high numbers of bacilli-has fallen sharply from a peak of close to 1 million ten years ago to only an estimated 70,000 worldwide in 1996.

Both these proposed changes have important implications for WHO's drive to eliminate leprosy as a public health problem by the year 2000, that is, to reduce the disease burden to less than 1 case per 10,000 population. WHO's Action Programme for the Elimination of Leprosy has reported that well over 97 per cent of known cases are being treated with MDT. The number of countries showing prevalence rates above 1 case per 10,000 population has fallen from 122 in 1985 to 55 at the beginning of 1997. Most of those countries have comparatively few cases, since 16 major endemic countries account for 91 per cent of the global leprosy burden. Besides the 8.4 million patients who have been cured, more than 1 million individuals have been saved by multidrug therapy from becoming disabled.