Contribution of relapses to total infection sources of leprosy in Guadeloupe

In Guadeloupe between 1970 and 1984, the incidence of new cases of leprosy, analysed through the computerization of data collected by the Leprosy Control Unit on OMSLEP record cards, showed a decline from 24 per 100,000 inhabitants in 1970 to 11 per 100,000 inhabitants in 1984 (y=-1.44). The decline was not significantly different in paucibacillary forms (y=-0.94) and in multibacillary forms (y=-0.45) but was much stronger among children below the age of 15 years (y=-3.22) than among adults (y=-0.67). During the same period 117 relapses were noted among the annual mean pool of 624 multibacillary patients who had been receiving lifelong treatment with dapsone alone for more than 5 years. The average number of relapses was 7.8 per year and the mean relapse rate 1.2% per year. The relapses have not in general been due to discontinuation of treatment by the patients because all cases of relapse for which a mouse inoculation has been carried out since 1980 harboured dapsone-resistant Mycobacterium leprae. Prevention of relapses by chemotherapy of inactive multibacillary cases still under treatment with dapsone alone appears as a priority for the control of leprosy in Guadeloupe.