Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review.
<h4>Background</h4>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 transmis...
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2021-05-01
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| Series: | PLoS Neglected Tropical Diseases |
| Online Access: | https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0009436&type=printable |
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| author | Thomas Hambridge Shri Lak Nanjan Chandran Annemieke Geluk Paul Saunderson Jan Hendrik Richardus |
| author_facet | Thomas Hambridge Shri Lak Nanjan Chandran Annemieke Geluk Paul Saunderson Jan Hendrik Richardus |
| author_sort | Thomas Hambridge |
| collection | DOAJ |
| description | <h4>Background</h4>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.<h4>Methodology/principal findings</h4>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.<h4>Conclusions/significance</h4>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. |
| format | Article |
| id | doaj-art-820d405af972450c9db47fa8fc2e693b |
| institution | OA Journals |
| issn | 1935-2727 1935-2735 |
| language | English |
| publishDate | 2021-05-01 |
| publisher | Public Library of Science (PLoS) |
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| series | PLoS Neglected Tropical Diseases |
| spelling | doaj-art-820d405af972450c9db47fa8fc2e693b2025-08-20T02:00:51ZengPublic Library of Science (PLoS)PLoS Neglected Tropical Diseases1935-27271935-27352021-05-01155e000943610.1371/journal.pntd.0009436Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review.Thomas HambridgeShri Lak Nanjan ChandranAnnemieke GelukPaul SaundersonJan Hendrik Richardus<h4>Background</h4>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.<h4>Methodology/principal findings</h4>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.<h4>Conclusions/significance</h4>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.https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0009436&type=printable |
| spellingShingle | Thomas Hambridge Shri Lak Nanjan Chandran Annemieke Geluk Paul Saunderson Jan Hendrik Richardus Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review. PLoS Neglected Tropical Diseases |
| 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 |
| url | https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0009436&type=printable |
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