Mosquito-borne and sexual transmission of Zika virus: Recent developments and future directions

•ZIKV is unusual in that it is transmitted by mosquitoes and through sex, which complicates ZIKV epidemiology.•Evidence supports rapid and widespread mosquito-borne transmission mostly from Aedes spp. in the current pandemic.•Sexual transmission is driven by ZIKV urogenital tropism in men, but likely causing differential disease in women. Zika virus (ZIKV; Genus Flavivirus, Family Flaviviridae) has recently emerged in Asia and the Americas to cause large outbreaks of human disease. The outbreak has been characterized by high attack rates, birth defects in infants and severe neurological complications in adults. ZIKV is transmitted to humans by Aedes mosquitoes, but recent evidence implicates sexual transmission as playing an important role as well. This review highlights the transmission of ZIKV in humans, with a focus on both mosquito and sexually-transmitted routes and their outcomes. We also discuss critical directions for future research.