Speaker
Description
Human immunodeficiency virus (HIV) causes substantial morbidity and mortality in sub-Saharan Africa. HIV cases were first reported in Madagascar, an island nation off Africa’s southeastern coast, in the 1990s, although current epidemiologic data are limited. However, high prevalence of commercial sex work, recent economic changes driving population mobility, and prevalence of other sexually transmitted infections present opportunities for rapid HIV spread.
Recent sequencing of HIV from a nationwide sample offers key insight into transmission dynamics. We conducted phylogeographic analyses of HIV transmission dynamics to identify the sources, number, and timing of introduction of viral subtypes to Madagascar. We included all publicly available sequences from Madagascar – comprising 695 sequences collected in 2005, 2012, and between 2019 and 2023 – alongside all available global partial sequences with complete coverage of the same genome regions which we obtained from the Los Alamos Sequence Database.
We reconstructed maximum clade credibility trees of protease (PR, ~250 bp), integrase (IN, ~750 bp), and reverse transcriptase (RT, ~900 bp) HIV-1 partial sequences for the four most identified subtypes in the Madagascar sequences (A [n=75,41,43 PR/IN/RT], B [n=37,25,31 PR/IN/RT], C [n=226,87,72 PR/IN/RT], G [n=21,54,40 PR/IN/RT]) using BEAST 2.7. We then conducted phylogeographic inference in BEAST 1.1, modeling both continent and country of origin as discrete traits. From these trees, we observed times to most recent common ancestor of several decades among Madagascar genomes included within each subtype investigated, suggesting multiple international introduction events to Madagascar. We also observed what appear to be local transmission clusters with more recent divergence times, including in the early 2000s for sequences collected in 2005 and in the late 2010s for the sequences collected between 2019 and 2023.
This work situates Madagascar’s HIV epidemic in the context of the global epidemic. There is an urgently developing HIV outbreak in Madagascar which requires further investigations of local dynamics.
| Expedited Notification | No thanks, I do not require Expedited Notification |
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