Phylogeogrphy reveals expansion of yellow fever virus genotypes in west and central africa

Yellow Fever virus remains the most medically significant Arbovirus in Africa, with the occurrence of large outbreaks with human fatalities in recent years in Africa. Molecular epidemiology has shown the presence of 4 genotypes circulating across Africa, however still paucity of data still exists, regarding directional spread and phylogeography of the African Yellow fever genotypes. The need to fill in this gap with information from recent spatiotemporal events from continuous occurrence of YF outbreaks in Africa conceptualized this study; which aims to investigate the most recent transmission events and directional spread of YF virus using updated genomic sequence data. Archived Yellow Fever sequence data was utilized along with epidemiologic data from outbreaks occurring between the years to analyze the case/fatality distribution over the study period. Phylogeograhic analysis was also utilized to demonstrate the ancestral introduction and geographic clustering of YF genotypes in Africa. Directional spread and geographic transmission of YF was also investigated. African YF genotypes were found to be geographical distinct, circulating within these distinct geographical boundaries. Spatiotemporal spread however revealed a westward spread of the West African genotypes over time, and recent northward movement of the East African genotype. We conclude by recommending expanded human/ vectoral surveillance of YF and other Arboviruses of public health importance, and upscaling sequencing capabilities of new and existing public health labs in Africa to help in the defense against public health threats. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Sources of data were openly available before the initiation of the study. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors