Dengue fever outbreaks have been repeatedly reported in Côte d'Ivoire. During the 2019 outbreak, DENV-1 was the predominant strain and phylogenetic analysis of the DENV-1 genome obtained from the present patient who returned to Japan in January 2019 revealed a high homology with the 2013-2014 Southeast Asian strains. In a previous outbreak in 2017, DENV-1 accounted for 5% of the DENV serotypes. The endemic DENV-1 strain in Abidjan in 2019 could be a strain that was imported from Southeast Asia. Dengue virus can spread globally, and imported dengue fever cases could serve as an alert for outbreaks in the exporting country.
Keywords: Côte d’Ivoire; Japan; Southeast Asia; dengue virus; phylogeny.