Leprosy Mailing List – September 29, 2022
Ref.: (LML) Existence of viable Mycobacterium leprae in natural environment and its genetic profiling in a leprosy endemic region
From: Pieter Schreuder and Ben Naafs, the Netherlands
Dear colleagues,
We like to draw your attention to the above-mentioned article about possible environmental reservoirs of M.leprae. As you may know, Paul Fine already mentioned the possibility of other reservoirs of M. leprae, outside the human and armadillo in 1982. Since then, many articles have appeared about possible animal and environmental reservoirs of M. leprae. However, a final judgement has not yet been made.
Paul Fine wrote in 1982 "Leprosy: The epidemiology of a slow bacterium" (Epidemiologic Reviews, Vol 4, 1982): "Although many questions remain unanswered, recent years have witnessed important advances in our understanding of the epidemiology of leprosy. The discovery of natural transmission of M. leprae in New World armadillos has challenged the traditional view of man as the only maintenance host. There is as yet no evidence that an extra human reservoir determines disease patterns in human populations, but this discovery alerts us to the possibility that other unusual species may harbor the organism. It may also raise difficulties for efforts to eliminate the infection from some regions."
A recent article by Ravindra P. Turankar et al named "Existence of viable Mycobacterium leprae in natural environment and its genetic profiling in a leprosy endemic region" (Frontiers in Tropical Disease, August 22) again points to the tantalizing possibility of an environmental reservoir playing a role in the transmission of M.leprae.
Enormous numbers of viable bacilli are expelled daily in the environment of untreated and relapsed lepromatous patients. There is also evidence to support excretion of bacilli from skin lesions. Also discharge from coughing and sneezing in the form of air-borne droplet may cause infection or settle in soil and water. But very limited information is available for the survival of bacilli outside the host. Existence of M. leprae DNA has been reported in water samples In Indonesia, India, Brazil. M. leprae, an obligate intracellular pathogen, have been shown to be associated with free living amoeba.
"This study found presence of viable M.leprae in inhabitant areas of leprosy patients. These viable bacilli might survive in the environment and may cause leprosy infection (disease) in a susceptible host. Similar genotype in clinical and environmental samples indicate that environment could possibly act as a source of infection. SNP and VNTR combination showed M.leprae strain similarities and their differentiation in certain blocks of Purulia. Such studies with the combination of genetic markers may provide a tool to track transmission link in the community."
Best regards,
Ben Naafs
Pieter Schreuder
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
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