Phylogeny of Dengue and Chikungunya viruses in Al Hudayda governorate, Yemen.

Yemen, which is located in the southwestern end of the Arabian Peninsula, is one of countries most affected by recurrent epidemics caused by emerging vector-borne viruses. Dengue virus (DENV) outbreaks have been reported with increasing frequency in several governorates since the year 2000, and the Chikungunya virus (CHIKV) has been also responsible of large outbreaks and it is now a major public health problem in Yemen. We report the results of the phylogenetic analysis of DENV-2 and CHIKV isolates (NS1 and E1 genes, respectively) detected in an outbreak occurred in Al-Hudayda in 2012. Estimates of the introduction date of CHIKV and DENV-2, and the phylogeographic analysis of DENV-2 are also presented. Phylogenetic analysis showed that the Yemen isolates of DENV belonged to the lineage 2 Cosmopolitan subtype, whereas CHIKV isolates from Yemen belonged to the ECSA genotype. All the CHIKV isolates from Yemen were statistically supported and dated back to the year 2010 (95% HPD: 2009-2011); these sequences showed an alanine in the aminoacid position 226 of the E1 protein. Phylogeographic analysis of DENV-2 virus showed that cluster 1, which included Yemen isolates, dated back to 2003 Burkina Faso strains (95% HPD 1999-2007). The Yemen, cluster dated back to 2011 (95% HPD 2009-2012). Our study sheds light on the global spatiotemporal dynamics of DENV-2 and CHIKV in Yemen. This study reinforces both the need to monitor the spread of CHIKV and DENV, and to apply significant measures for vector control.