Spread by the bite of infected mosquitos, hundreds of millions of people are infected by flaviviruses every year, resulting in tens of thousands of deaths and billions of dollars of lost economic output
While the flavivirus family is large and diverse, dengue virus (DENV) and Zika virus (ZIKV) are the two members that remain widespread, significant, and persistent public health challenges. Both DENV and ZIKV are most commonly found in the tropics and sub-tropics. However, factors such as climate change and increased global travel means that outbreaks of these viruses are now observed in Europe and the United States.
Zika virus (ZIKV) is closely related to DENV and can be transmitted by the same family of mosquitos
Most ZIKV infections are mild or asymptomatic in healthy/immunocompetent patients but is associated with Guillain-Barré syndrome, neuropathy and myelitis in a fraction of infected individuals
However, ZIKV infection during pregnancy can result in significant harm to the developing fetus, including microcephaly and other congenital malformations as well as preterm birth and miscarriage
Microcephaly and other congenital malformations are associated with virus transmission from the mother’s bloodstream, across the placenta, to the developing fetus.
While the factors that influence maternal/fetal transmission of ZIKV are incompletely understood, increasing evidence – including recent non-human primate studies – suggest that ZIKV-reactive IgG antibodies generated by prior flavivirus infections can facilitate fetal ZIKV infection by shepherding the virus across the placenta as part of antibody/virus immune complexes (Reference One, Reference Two)
