RELAPSE AFTER LONG-TERM FOLLOW-UP OF MULTIBACILLARY PATIENTS TREATED BY WHO MULTIDRUG REGIMEN

Thirty-five multibacillary (MB) leprosy patients were treated with 2 y ears of multidrug therapy (MDT) and followed up regularly for relapse. Relapse was defined as: a) an increase of the bacterial index (BI) by 2+ over the previous value from any single site of old lesions and b) the occurrence of definite new skin lesion(s) which demonstrated a hi gher BI than any pre-existing lesion. After a mean duration of 72.7 +/ - 17.3 months of follow up per patient, seven relapses were diagnosed; the mean incubation period of relapse was 62.7 +/- 18.7 months. The o verall relapse rate was 20.0% (or 3.3 per 100 patient-years), very sig nificantly higher than the figures obtained from the same group of pat ients analyzed 2 1/2 years earlier, indicating that relapses occurred late (at least 5 +/- 2 years) after stopping MDT. Further analysis ind icated that the relapse rate was closely correlated with the bacterial load of the patient, occurring far more frequently among patients wit h a BI of greater than or equal to 4.0 before MDT or with a BI of grea ter than or equal to 3.0 at the end of MDT. To avoid the alarmingly hi gh relapse rate, it is proposed that the duration of MDT be doubled to 4 years in patients with an average BI of greater than or equal to 4. 0 before MDT.