Relapse study in smear positive multibacillary (MB) leprosy after 1 year WHO-multi-drug therapy (MDT) in Cebu, Philippines.

OBJECTIVE To determine the frequency, time interval to relapse and the possible risk factors for relapse in multibacillary (MB) leprosy after 1 year's treatment with the standard multi-drug therapy (MDT). MATERIALS AND METHODS Smear positive MB patients treated with MDT for 1 year were enrolled in a prospective relapse study between 1999 and 2005 at the Leonard Wood Memorial Center for Leprosy Research (LWM). After treatment completion, at yearly intervals, patients underwent slit-skin smear examination and were clinically monitored for possible signs of relapse. RESULTS 300 patients were recruited, and by 2009, follow-up totaled 1,913 patient years, with a mean of 6.4 years per patient. Only one case of relapse was detected, with an absolute relapse rate of 0.3% (0.52 per 1000 patient-years at risk (PYAR)); among a subset with pre-treatment bacterial indices (BI) of > or = 4 +, the rate was 0.6%. Relapse occurred 7 years after MDT. CONCLUSION These data provide strong evidence of the long-term efficacy of the one year WHO-MDT for multibacillary (MB) leprosy patients, even in those with a high initial BI.