The Zika virus epidemic that started in Brazil in 2014 has spread to >30 countries and territories in Latin America, leading to a rapid rise in the incidence of microcephalic newborns and adults with neurological complications. At the beginning of the outbreak, little was known about Zika virus morphology, genome structure, modes of transmission, and its potential to cause neurological malformations and disorders. With the advancement of basic science, discoveries of the mechanisms of strain variability, viral transfer to the fetus, and neurovirulence were published. These will certainly lead to the development of strategies to block vertical viral transmission, neuronal invasion, and pathogenesis in the near future. This paper reviews the current literature on Zika virus infections, with the aim of gaining a holistic insight into their etiology and pathogenesis. We discuss Zika virus history and epidemiology in Brazil, viral structure and taxonomy, old and newly identified transmission modes, and neurological consequences of infection.

Sexual transmission of Zika virus (ZIKV) is a matter of great concern. Infectious viral particles can be shed in semen for as long as six months after infection and can be transferred to male and female sexual partners during unprotected sexual intercourse. The virus can be found inside spermatozoa and could be directly transferred to the oocyte during fertilization. Sexual transmission of ZIKV can contribute to the rise in number of infected individuals in endemic areas as well as in countries where the mosquito vector does not thrive. There is also the possibility, as has been demonstrated in mouse models, that the vaginal deposition of ZIKV particles present in semen could lead to congenital syndrome. In this paper, we review the current literature to understand ZIKV trafficking from the bloodstream to the human male reproductive tract and viral interactions with host cells in interstitial spaces, tubule walls, annexed glands and semen. We hope to highlight gaps to be filled by future research and potential routes for vaccine and antiviral development.