Chemoprophylaxis of leprosy in the Southern Marquesas with a single 25 mg/kg dose of rifampicin. Results after 10 years

In 1988, a programme of leprosy chemoprophylaxis, employing a supervised, s ingle 25 mg/kg dose of rifampicin, was implemented in the Southern Marquesa s Islands. Of the 2786 inhabitants, 2751 (98(.)7%) were treated. In additio n, 3144 South Marquesans living elsewhere in French Polynesia were administ ered the same chemoprophylaxis. During the following 10 years, seven lepros y patients were detected among those who had been administered chemoprophyl axis. Of these, two were very likely missed cases of leprosy, and cannot be considered a failure of chemoprophylaxis. The epidemiometric projection mo del, based on cases of leprosy observed in the Southern Marquesas during th e 20 years preceding implementation of the programme, predicted that 17 lep rosy cases could be expected in the South Marquesan population if no chemop rophylaxis were given. In fact, only five cases were detected in the treate d population, a number significantly smaller than 17, suggesting that the c hemoprophylaxis was 70% effective, assuming that no change of detection rat e would have occurred without chemoprophylaxis. However, during the 10 year s following implementation of the chemoprophylaxis programme, the detection rate in the Polynesian population that was not administered chemoprophylax is declined by about 50%. Therefore, the effectiveness of the chemoprophyla xis was only 35-40%.