Zika virus and reproduction: facts, questions and current management.

BACKGROUND: Zika virus (ZIKV) is an arthropod-borne virus of the family Flaviviridae, genus Flavivirus. ZIKV is currently the focus of an ongoing pandemic and worldwide public health emergency. Although originally isolated in 1947, its pathogenesis was poorly known and very few documented infections were published until recently. Its route of transmission and its impact on reproduction and pregnancy have only recently begun to be disclosed.

OBJECTIVE AND RATIONALE: This review summarizes the most recent knowledge about ZIKV infection and pathogenesis and focuses on its impacts on male and female genital tracts, including the risks of sexual transmission and to pregnancy. The consequences of ZIKV infection for pregnancy planning and ART are also discussed.

SEARCH METHODS: The PubMed and EMBASE databases were inter-rogated using specific terms, such as 'ZIKV', 'transmission', 'male', 'female', fertility', 'pregnancy, 'semen', 'testis', 'ovary' and 'genital tract', up to 17 March 2017.

OUTCOMES: ZIKV has long been considered a harmless virus, but increasing evidence suggests that it has adverse effects on the neurological system and on pregnancy outcomes. In mice, ZIKV slows foetal growth and damages the foetal brain. In humans, the virus is able to cross the placental barrier and to induce foetal death and major anomalies, such as microcephaly, brain defects and long-term neurologic sequelae, i.e. the 'congenital Zika syndrome'. In addition to its transmission by mosquitoes, ZIKV may be transmitted sexually. Currently available data indicate that ZIKV RNA can remain detectable in semen for several months, whereas shedding in the female genital tract appears to be rare and of short duration. Current guidance on preventing the sexual transmission of ZIKV is based on the assumption that transmission occurs from a male partner to a receptive partner. Furthermore, in mouse models, the virus can actively replicate in male genital organs and induce severe orchitis, which raises concerns about its possible impact on human male fertility.

WIDER IMPLICATIONS: These new and relevant findings have led many countries and institutions to release updated and regular guidance for preconception counselling and ART to prevent the sexual transmission of ZIKV. Progress in understanding the sexual transmission of ZIKV and its dissemination to genital systems would also help to better anticipate and control outbreaks of potentially sexually transmissible infectious agents.