Tracing the Evolution and Circulation of Measles Virus in Africa

Abstract Measles remains a significant public health challenge in Africa, threatening global elimination goals. Leveraging the WHO/GMRLN network and sequencing 336 MeV strains, we conducted a comprehensive phylodynamic analysis to reconstruct viral transmission across the continent. African MeV lineages are genetically distinct, circulating in a smooth gradient driven by human mobility rather than isolation. Phylogeographic inference identified at least nine independent intercontinental introductions into Africa between 2008–2018, primarily from Asia (six events), with the Asia-Democratic Republic of the Congo (DRC) corridor showing the highest frequency. Crucially, we quantified extended periods of cryptic transmission (up to 5.13 years in Cameroon) and viral persistence (up to 8.78 years for the Nigeria-to-Cameroon seeding event). Strong correlations link persistence to undetected circulation (r = 0.82) and cases to deaths (r = 0.98). These findings highlight the need for enhanced surveillance and vaccination campaigns to interrupt covert, sustained transmission chains and prevent global dissemination.