Leprosy Mailing List – September 2, 2024
Ref.: (LML) Post-Exposure Prophylaxis in Leprosy
From: Ben Naafs, Munnekeburen, the Netherlands
Dear Pieter,
As you know I am not in favour of PEP. But less aggressive than some. Most of the papers are not convincing. Usually done under conditions that are favourable for a positive outcome. And still the researchers continue to proof their point by continuously increasing the strength of their "medication". The last article of Epco Hasker, for LML readers who have missed it, is enclosed.
Research that was a success was the Malta trial. Eradication was achieved and claimed by Freerksen in 1977(1). But that was treatment! It was assessed by Leiker and he showed me that in the tunica dartos of the scrotum of LL patients still intact Mycobacteria were present (Personal communication 1988). But why these patients did not relapse is for me interesting (2).
We assume that under favourable conditions the persisters start dividing. But which are the favourable conditions. Contact with M. leprae in the environment could be one. Or even contact with other mycobacteria which might influence the condition of the patients. We have found an indication in Zimbabwe working with Elisa and antigens supplied by John Stanford in 1985 (3). Some bacteria protected and some seem to enhance (4).
All these factors are present in the PEP trials and influence the outcome. Important is to follow the ones participating in a trial for longer than two years. And then look also at the housing and compound. M.leprae cannot survive on concrete floor and has difficulties in dry conditions. It survives in moist environment and in pools. Houses with mud floors in moist conditions are ideal. Up and down going of the immune system due to malnutrition, infections, medication or vaccination could be a triggering factor.
Among all this, there is another problem, 80% of the individuals do genetically not develop leprosy. Maybe that within a leprosy family it might be less. But I studied and published with Stoner that lived in a family where both parents have leprosy. With the primitive methods we had at that time (1970Th) were indeed from this father and mother. Some developed leprosy and others not. Some BT and some even polar LL (5).
Thus, when you do a PEP trial and need statistics to proof, forget about it. Cost a lot of money and gives hope to the participants. But most research show that the effect is only for a short time. The people will be disappointed and will lose trust in modern medicine and their own leprosy workers.
Is it worth it?
Ben
References
1. Freerksen E, Rosenfeld M. Leprosy eradication project of Malta. First published report after 5 years running. Chemotherapy. 1977;23(5):356-86. doi: 10.1159/000222005. PMID: 332467.
2. Jamet P; Blanc L.; Faye O, Traore I., Bobin P. Single dose Rifampin cannot prevent relapse in skin smear-negative Multibacillary Leprosy after dapsone monotherapy. Abstract International Leprosy Congress 1993 CH 21.
3. Lyons NF, Naafs B. Influence of environmental mycobacteria on the prevalence of leprosy clinical type. Int J Lepr Other Mycobact Dis. 1987 Dec;55(4):637-45. PMID: 3430001
4. Mous HVH, Mason P.R., De Lange WE, Gwanzura, L. Naafs, B. Sensitization to mycobacteria in 2 area's of Zimbabwe with different distribution of leprosy type and leprosy incidence: skin tests. Abstract International Leprosy Congress 1993 IN 175.
5: Stoner GL, Touw J, Belehu A, Naafs B. In-vitro lymphoproliferative response to Mycobacterium leprae of HLA-D-identical siblings of lepromatous leprosy patients. Lancet. 1978 Sep 9;2(8089):543-7. doi: 10.1016/s0140-6736(78)92881-7. PMID: 79915.
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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