Dapsone syndrome in Vanuatu: a high incidence during multidrug treatment (MDT) of leprosy.

Side-effects of leprosy treatment with dapsone are said to be uncommon, with drug allergy occurring in only one of every several hundred patients treated with dapsone. The dapsone or sulphone syndrome (DDS) has been recognized since the earliest days of sulphone therapy but until recently its incidence had been decreasing. In Vanuatu, during the years 1988-1991, nine leprosy patients have developed the dapsone syndrome, four of whom have died. During the last 4 years only 37 patients were started on treatment, which is an incidence of the dapsone syndrome of 24% with a fatality rate of 11%. All the patients were being given multi-drug treatment (MDT) of daily dapsone (100 mg) and clofazimine (50 mg) and monthly rifampicin (600 mg) and clofazimine (300 mg). There has been speculation that the increased incidence of what was previously described as a rare reaction is due to the use of MDT, and the reasons for this are discussed. We feel the increase in the number of reactions in Vanuatu since starting MDT is probably due to the high starting dose of 100 mg of dapsone, possibly enhanced by the combination with clofazimine and rifampicin and a genetic susceptibility of the Melanesian population.