Zika Virus Outbreak, Bahia, Brazil

To the Editor: Zika virus (ZIKV) is a mosquito-borne flavivirus related to yellow fever virus, dengue virus (DENV), and West Nile virus (WNV). It is a single-stranded positive RNA virus (10,794-nt genome) that is closely related to the Spondweni virus and is transmitted by many Aedes spp. mosquitoes, including Ae. africanus, Ae. luteocephalus, Ae. hensilli, and Ae. aegypti. The virus was identified in rhesus monkeys during sylvatic yellow fever surveillance in the Zika Forest in Uganda in 1947 and was reported in humans in 1952 (1).