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Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review

BACKGROUND: Leprosy is an infectious disease caused by Mycobacterium leprae. As incidence begins to decline, the characteristics of new cases shifts away from those observed in highly endemic areas, revealing potentially important insights into possible ongoing sources of transmission. We aimed to i...

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Autores principales: Hambridge, Thomas, Nanjan Chandran, Shri Lak, Geluk, Annemieke, Saunderson, Paul, Richardus, Jan Hendrik
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8186771/
https://www.ncbi.nlm.nih.gov/pubmed/34038422
http://dx.doi.org/10.1371/journal.pntd.0009436
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author Hambridge, Thomas
Nanjan Chandran, Shri Lak
Geluk, Annemieke
Saunderson, Paul
Richardus, Jan Hendrik
author_facet Hambridge, Thomas
Nanjan Chandran, Shri Lak
Geluk, Annemieke
Saunderson, Paul
Richardus, Jan Hendrik
author_sort Hambridge, Thomas
collection PubMed
description BACKGROUND: Leprosy is an infectious disease caused by Mycobacterium leprae. As incidence begins to decline, the characteristics of new cases shifts away from those observed in highly endemic areas, revealing potentially important insights into possible ongoing sources of transmission. We aimed to investigate whether transmission is driven mainly by undiagnosed and untreated new leprosy cases in the community, or by incompletely treated or relapsing cases. METHODOLOGY/PRINCIPAL FINDINGS: A literature search of major electronic databases was conducted in January, 2020 with 134 articles retained out of a total 4318 records identified (PROSPERO ID: CRD42020178923). We presented quantitative data from leprosy case records with supporting evidence describing the decline in incidence across several contexts. BCG vaccination, active case finding, adherence to multidrug therapy and continued surveillance following treatment were the main strategies shared by countries who achieved a substantial reduction in incidence. From 3950 leprosy case records collected across 22 low endemic countries, 48.3% were suspected to be imported, originating from transmission outside of the country. Most cases were multibacillary (64.4%) and regularly confirmed through skin biopsy, with 122 cases of suspected relapse from previous leprosy treatment. Family history was reported in 18.7% of cases, while other suspected sources included travel to high endemic areas and direct contact with armadillos. None of the countries included in the analysis reported a distinct increase in leprosy incidence in recent years. CONCLUSIONS/SIGNIFICANCE: Together with socioeconomic improvement over time, several successful leprosy control programmes have been implemented in recent decades that led to a substantial decline in incidence. Most cases described in these contexts were multibacillary and numerous cases of suspected relapse were reported. Despite these observations, there was no indication that these cases led to a rise in new secondary cases, suggesting that they do not represent a large ongoing source of human-to-human transmission.
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spelling pubmed-81867712021-06-16 Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review Hambridge, Thomas Nanjan Chandran, Shri Lak Geluk, Annemieke Saunderson, Paul Richardus, Jan Hendrik PLoS Negl Trop Dis Research Article BACKGROUND: Leprosy is an infectious disease caused by Mycobacterium leprae. As incidence begins to decline, the characteristics of new cases shifts away from those observed in highly endemic areas, revealing potentially important insights into possible ongoing sources of transmission. We aimed to investigate whether transmission is driven mainly by undiagnosed and untreated new leprosy cases in the community, or by incompletely treated or relapsing cases. METHODOLOGY/PRINCIPAL FINDINGS: A literature search of major electronic databases was conducted in January, 2020 with 134 articles retained out of a total 4318 records identified (PROSPERO ID: CRD42020178923). We presented quantitative data from leprosy case records with supporting evidence describing the decline in incidence across several contexts. BCG vaccination, active case finding, adherence to multidrug therapy and continued surveillance following treatment were the main strategies shared by countries who achieved a substantial reduction in incidence. From 3950 leprosy case records collected across 22 low endemic countries, 48.3% were suspected to be imported, originating from transmission outside of the country. Most cases were multibacillary (64.4%) and regularly confirmed through skin biopsy, with 122 cases of suspected relapse from previous leprosy treatment. Family history was reported in 18.7% of cases, while other suspected sources included travel to high endemic areas and direct contact with armadillos. None of the countries included in the analysis reported a distinct increase in leprosy incidence in recent years. CONCLUSIONS/SIGNIFICANCE: Together with socioeconomic improvement over time, several successful leprosy control programmes have been implemented in recent decades that led to a substantial decline in incidence. Most cases described in these contexts were multibacillary and numerous cases of suspected relapse were reported. Despite these observations, there was no indication that these cases led to a rise in new secondary cases, suggesting that they do not represent a large ongoing source of human-to-human transmission. Public Library of Science 2021-05-26 /pmc/articles/PMC8186771/ /pubmed/34038422 http://dx.doi.org/10.1371/journal.pntd.0009436 Text en © 2021 Hambridge et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Hambridge, Thomas
Nanjan Chandran, Shri Lak
Geluk, Annemieke
Saunderson, Paul
Richardus, Jan Hendrik
Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review
title Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review
title_full Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review
title_fullStr Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review
title_full_unstemmed Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review
title_short Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review
title_sort mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: a systematic review
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8186771/
https://www.ncbi.nlm.nih.gov/pubmed/34038422
http://dx.doi.org/10.1371/journal.pntd.0009436
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