Abstract
Globally, 390 million people are at risk of dengue infection and over the past 50 years the virus incidence increased thirty-fold. In Senegal, an unprecedented occurrence of outbreaks and sporadic cases have been noticed since 2017. In October 2018 an outbreak of Dengue virus 2 (DENV-2) was reported in the north of Senegal affecting multiple areas including Saint-Louis, Richard Toll and Rosso whichare located at the border with Mauritania. Of these 173 blood specimen samples collected from patients, 27 were positive for dengue by qRT-PCR and eight were serologically confirmed to be positive for DENV IgM. Serotyping using qRT-PCR reveals that isolates were positive for DENV-2. A subset of DENV-2 positive samples were selected and subjected to whole-genome sequencing followed by phylogenetic analysis. Analysis of 6 nearly complete genome sequences revealed that the isolates belong to the cosmopolitan genotype and are closely related to the Mauritanian strains detected between 2017 and 2018 and those detected in many West African countries such as Burkina Faso or Cote d'Ivoire. Our results suggest a transboundary circulation of the DENV-2 cosmopolitan genotype between Senegal and Mauritania and call for a need of coordinated surveillance of arboviruses between these two countries. Interestingly, high level of homology between West African isolates highlights endemicity and calls for the set-up of sub-regional viral genomic surveillance which will lead to a better understanding of viral dynamics, transmission and spread across Africa.
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