Bacillary Index

 

Leprosy Mailing List – March 11,  2013

Ref.:    (LML) Bacillary Index

From:  Herman-Joseph Kawuma, GLRA, Uganda

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Dear Pieter,

 

 

I would like to refer to the letter of Dr. Castro about the Bacillary Index of March 11, 2013.

 

It is known for some years that the calculation of BI as is currently done is mathematically incorrect and many clinicians would be interested in recording the actual BI from each site (the individual numbers from which the arithmetic mean is derived). The awareness of diminished usage of slit skin smears, the absence of a quality assurance mechanism and other inherent inconsistencies have come up in the discussion of the definition of a leprosy relapse based on clinical signs and a change in skin smear results. 

 

I am not aware of any particular reason why nasal smears/nose blows/smear of nasal secretions should not be graded using the same methodology.

 

The scoring system in common use does not employ the terminology" at least" but rather gives a range:

>1000/field as BI 6+, 100-1000/field as BI 5+, 10-100/field as BI 4+, 1-10/field as BI 3+ etc.,  up to 0/100 fields as BI 0. It would be also erroneous to grade a smear 0 or 1 without examining at least 100 fields!

 

Dr. Castro does not describe clearly how the Colombian grading system differs from the one above; a more detailed description (instead of "like in TB" might invite some more discussions of the subject.

 

Regards,

 

 

H Joseph Kawuma

GLRA, Uganda

 

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