Leprosy Mailing List – , 2021
Ref.: (LML) Leprosy Cure
From: Narasimba Rao, Hyderabad, India
Dear Pieter,
Ref to the mail of Dr Laila LML dated 7th May 2021
It is not the answer that enlightens, but the question." – Eugene Ionesco
Dr Laila wanted to know where one can find more information about the criteria for clinical cure, laboratory cure of the disease. It is an important question. Every leprosy worker need to ponder over it, as it pertains each and every PAL, for whom the programme is designed. . I would like to put forward my views
Cure can be A. clinical cure B. Bacteriological cure C. Histological cure D. Serological cure. Of these, I would like to disregard the last one and elaborate on the first three.
Clinical cure – in theory could be observed in all types of patients, if looked for carefully, when it occurs. (Now, it should be very simple! but it is not. Because it depends on the initial clinical features noted and vary for each type of leprosy. For example neither hypoesthesia (its sequels) nor hypopigmentation/ nerve thickening/ disability regress completely in years after completion of prescribed MDT. Hence, cessation of activity of disease is considered as clinical cure. However, there is no accepted list/ consensus to define signs are activity. But they are there.
Bacteriological cure: First of all, skin smear (SS) services should be available, which were abandoned, globally. Hence, the discussion below pertains to those centers that have SS facility.
A definition in the programme states that Increase in BI by 2 logs is considered as relapse after therapy. But fall by 2 logs is not bacteriological cure. Only a BI of zero can be cure. But researchers haggle over morphology of AFB when observed; solid, fragmented, granular; to decide on their viability vis a vis cure/non-infectivity of the patient. And to be fair it could be the right method, but practically deciphering MI is not an easy job.
To top it, SS is positive only in some percentage of MB patients and always negative in PB group (who are about 50% of leprosy patients world over). Hence SS values cannot be a basis for cure in PB group and some part of MB group who happen to be smear negative, if it is performed at all.
Histological Cure: Based on Skin biopsy
Good news is that it can help to some extent in all types of leprosy, except in pure neuritic leprosy, wherein nerve biopsy is needed. Bad news is that WHO/ most national leprosy programmes are yet to give skin histopathology a status, either in defining relapse or cure or for deciding on type of MDT needed for the patient. On the whole, it is a neglected parameter. Reason..? Ummm… It is complicated!!
There is a need for initial and follow-up skin/nerve biopsy records to decide cure. And anyway, very few biopsies are performed in field in general. Moreover, special stains for AFB and trained pathologist, nay, a leprosy pathologist is needed to study and decipher them. Only possible in few tertiary-care centers.
In Conclusion, of all the above mentioned methods, skin smear bacteriology (bacilloscopy) is the most dependable, as many country-specific programmes rely on them. Even WHO depended on it in 1982 to 1998, with great success.
Even today, countries like US, japan, England among others, do perform skin smears and as per their programme guidelines, and provide treatment based on skin smear status, sometimes up to smear negativity, indicating that it is the most followed parameter to define cure.
On the whole, about 1/4th to 1/3rd of all leprosy patients are smear positive and they are the most important reservoir of M leprae globally and the cause of transmission in the community. And it is sad that SS is not part of global programme anymore! Even the latest Global strategy 2021-2030 does not mention to re-start it globally. Only talks of strengthening it, whatever that means!
With best regards
P Narasimha Rao MD PhD
President, Indian Association of leprologists.
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
Contact: Dr Pieter Schreuder << editorlml@gmail.com
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