Yellow Fever Outbreak in Eastern Senegal, 2020-2021.

Moussa Moïse Diagne,El Hadji Ndiaye,Cheikh Tidiane Diagne,Diawo Diallo,Vida Ahyong,Mamadou Aliou Barry,Mawlouth Diallo,Cristina M Tato,Alioune Gaye,Amadou Diallo,Oumar Faye,Cheikh Loucoubar,Fodé Danfakha,Amadou Alpha Sall,Marie Henriette Dior Ndione,Babacar Diouf,Mamadou Diop,Scott C Weaver,Boly Diop,Moufid Mhamadi,Gamou Fall,Lusajo Mwakibete

doi:10.3390/v13081475

Moussa Moïse Diagne, El Hadji Ndiaye + Show 20 more

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https://doi.org/10.3390/v13081475

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Abstract

Yellow fever virus remains a major threat in low resource countries in South America and Africa despite the existence of an effective vaccine. In Senegal and particularly in the eastern part of the country, periodic sylvatic circulation has been demonstrated with varying degrees of impact on populations in perpetual renewal. We report an outbreak that occurred from October 2020 to February 2021 in eastern Senegal, notified and managed through the synergistic effort yellow fever national surveillance implemented by the Senegalese Ministry of Health in collaboration with the World Health Organization, the countrywide 4S network set up by the Ministry of Health, the Institut Pasteur de Dakar, and the surveillance of arboviruses and hemorrhagic fever viruses in human and vector populations implemented since mid 2020 in eastern Senegal. Virological analyses highlighted the implication of sylvatic mosquito species in virus transmission. Genomic analysis showed a close relationship between the circulating strain in eastern Senegal, 2020, and another one from the West African lineage previously detected and sequenced two years ago from an unvaccinated Dutch traveler who visited the Gambia and Senegal before developing signs after returning to Europe. Moreover, genome analysis identified a 6-nucleotide deletion in the variable domain of the 3′UTR with potential impact on the biology of the viral strain that merits further investigations. Integrated surveillance of yellow fever virus but also of other arboviruses of public health interest is crucial in an ecosystem such as eastern Senegal.

Highlights

Yellow fever virus (YFV) is a mosquito-borne flavivirus (Flaviviridae family) first isolated in 1927 from a male patient [1].Mature virions of 40 nm diameter are icosahedral and comprise a nucleocapsid, composed of capsid (C) protein subunits, surrounded by a lipid bilayer derived from host membranes
A sample from a 40-year-old woman from the Kidira district in Tambacounda medical region suspected to have an arboviral infection was collected on 3 October 2020, and sent to the WHO Collaborating Center of Reference and Research on Arboviruses and Hemorrhagic Fever Viruses in the Virology Department of the Institut Pasteur de Dakar for diagnostic
YFV acute infection was diagnosed with positive results forboth RT-qPCR and enzymelinked immunosorbant assay (ELISA) + plaque reduction neutralization tests (PRNTs) assays

Summary

Introduction

Mature virions of 40 nm diameter are icosahedral and comprise a nucleocapsid, composed of capsid (C) protein subunits, surrounded by a lipid bilayer derived from host membranes. The viral envelope is studded with dimers of the envelope (E) glycoprotein and membrane (M) protein [2]. YFV is a positive-sense, single stranded RNA ([+]ssRNA) virus with a genome approximatively 11kb in length [3]. The structural proteins (C, M, and E) and the nonstructural (NS) proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) are encoded in a single open reading frame (ORF) after production of a polyprotein subsequently processed by proteolytic cleavage [3]. The ORF is flanked by two non-coding ends with a cap-structure at the 5‘ terminus and a very stable stem loop in the 3 terminus necessary for genome stabilization and initiation of both translation and RNA synthesis [4]

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