Diagnosing multibacillary leprosy: a comparative evaluation of diagnostic accuracy of slit-skin smear, bacterial index of granuloma and WHO operational classification.

Background: In view of the relatively poor performance of skin smears WHO adopted a purely clinical operational classification, however the poor specificity of operational classification leads to overdiagnosis and unwarranted overtreatment while the poor sensitivity leads to underdiagnosis of multibacillary (MB) cases with inadequate treatment. Bacilli are more frequently and abundantly demonstrated in tissue sections.

Aims And Methods: We compared WHO classification, slit-skin smears (SSS) and demonstration of bacilli in biopsies (bacterial index of granuloma or BIG) with regards to their efficacy in correctly identifying multibacillary cases.