Co-circulation of Dengue and Chikungunya Viruses

V infections are not uncommon in the Middle East (1). In particular, recurrent outbreaks of dengue fever have been reported on the Arabian Peninsula since 1990 (2). In Yemen, dengue virus (DENV) infections have reemerged with higher frequency during the last decade (3); in 2010, during a dengue outbreak that occurred in the southern governorate of Hadramout (4), cases of dengue hemorrhagic fever were identified (5). In 2010– 2011, another mosquitoborne virus, the chikungunya virus (CHIKV), was detected in febrile patients in Al Hudaydah, Yemen (6). To evaluate to what extent these arboviruses are involved in dengue-like illness outbreaks in Yemen, we conducted a study in Al Hudaydah.