The pattern of decline in bacillary index after 2 years of WHO recommended multiple drug therapy: the AMFES cohort.
With effective antibiotic treatment, the bacillary index (BI) in multibacillary leprosy patients declines over a number of years. This can be quantified as a rate of decline in log-units per year or as the time until smear negativity 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 negativity. 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 the first 2 years after diagnosis, the mean rate of decline was 1.15 units per 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 determined by the initial BI and classification, making it a less useful indicator of bacterial clearance. More severe impairment at the start of treatment was associated with a faster return to smear negativity, for which no obvious explanation can be given. Reversal reactions, which occurred in 25% of the cases reviewed, are not associated with a more rapid clearance of bacilli.
Amenu
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ALERT, Addis Ababa, Ethiopia.
Saunderson
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Desta
K
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Byass
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P
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015331:Cohort Studies; D015169:Colony Count, Microbial; D016001:Confidence Intervals; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015994:Incidence; D007917:Leprostatic Agents / Q000627:therapeutic use*; D007918:Leprosy / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009166:Mycobacterium leprae / Q000187:drug effects / Q000302:isolation & purification*; D012307:Risk Factors; D012867:Skin / Q000382:microbiology; D014944:World Health Organization
D007917:Leprostatic Agents