The pattern of decline in bacillary index after 2 years of WHO recommendedmultiple drug therapy: the AMFES cohort

With effective antibiotic treatment, the bacillary index (BI) in multibacil lary leprosy patients declines over a number of years. This can be quantifi ed as a rate of decline in log-units per year or as the time until smear ne gativity is reached. in the AMFES cohort 220 cases had data on the changes in their BI over time, while 170 cases are documented until smear negativit y. The average BI at the start was 3.3( SD 1.5; range 0.3-5.5) and the mean rate of decline was 0.85 units per year (median 0.7 units per year); in th e first 2 years after diagnosis, the mean rate of decline was 1.15 units pe r year. The rate of decline was not related to any clinical features of the disease except delay in diagnosis: patients presenting for treatment early had a significantly faster rate of clearing the bacilli (adjusted relative risk 2.3; 95% CI 1.0-5.1). Fifty-eight percent of cases took longer than 3 years to reach smear negativity, but this time interval is largely determi ned by the initial BI and classification, making it a less useful indicator of bacterial clearance. More severe impairment at the start of treatment w as associated with a faster return to smear negativity, for which no obviou s explanation can be given. Reversal reactions, which occurred in 25% of th e cases reviewed, are not associated with a more rapid clearance of bacilli .