Pattern of bacillary clearance in multibacillary leprosy patients with multidrug therapy

The bacteriological index (BI) of the skin smears is traditionally one of the important parameters of assessment of severity and of progress of leprosy under multidrug therapy. The present study reports on BI clearance among 578 multibacillary treated leprosy patients and the factors that influence this clearance. The patients were treated till smear negativity or for 2 years fixed duration and their skin smears periodically examined every 6 to 12 months till negativity (and even afterwards). We confirm that bacterial clearance is a slow process. The time taken for each log-unit decline in BI is between 13.6 to 24 months probably depending on initial BI level. The rate of smear negativity appears to be dependent on immune competence of the patients as reflected by a rapid BI decline in borderline BT-BB patients vis-à-vis BL-LL lepromatous patients both in the low and high BI group. Patients who had several episodes of ENL, took significantly longer time (63.7 months versus 53.5 months, p<0.0001) to become smear negative than those without ENL.