Leprosy Mailing List – October 6, 2018
Ref.: (LML) Ultra-violet radiation, small islands & armadillo corpses
From: Joel Almeida, London and Mumbai
M. leprae are known to remain viable for longer in shaded environments than in sunlit environments. Their reduced genome and consequent dependence on catabolic products from host cells paradoxically seems to endow them with the ability to enter a dormant state readily and to survive in that state for months or even longer. The propensity of M. leprae to enter dormancy is capable of explaining many otherwise puzzling features of the epidemiology, microbiology and differential rate of response to bactericidal drugs with duration of treatment.
Ultra-violet radiation is capable of disrupting bacterial DNA regardless of the metabolic state of the organism.
Therefore, uv radiation seems to deserve a trial as a means of killing dormant but viable M. leprae in shaded environments, both indoors and outdoors. Leprosy hot spots in forested or shaded urban areas of endemic countries might be prime candidates for pilot trials.
Wouldn't it be good if uv radiation of the indoor and outdoor environment in the neighbourhood of recognised sources of M. leprae turned out to have a measurable impact on the incidence rate of leprosy among contacts? Trials should help evaluate the potential of this approach.
Also, the WHO goodwill ambassador has issued an appeal to help small islands get rid of leprosy. This seems sensible, because it will yield very important lessons about the microbiology and epidemiology whether or not we succeed in eradicating M. leprae from a small island. uv radiation could help there too, in disinfecting areas around known sources of M. leprae.
The US-controlled islands that have a high incidence rate of leprosy might well be considered by the CDC USA for a concerted effort at eradication. uv radiation could form part of the effort there too.
There may well be other endemic areas or hot spots where uv radiation is worth a trial. Armadillo corpses seem like a prime candidate for this kind of disinfection.
uv radiation might reach the M. leprae that remain unaffected by all currently recognised strategies.
Dear colleagues, I will go on holiday till the second week of November. It will not be possible to publish any letter or communication in that period. Sorry for that.
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
Contact: Dr Pieter Schreuder << firstname.lastname@example.org
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