Congenital Zika Virus Infection Paradigm: What is in the Wardrobe? A Narrative Review

Background: Zika virus infection during pregnancy has been recently associated with congenital microcephaly and other severe neural tube defects. However, the magnitude of confirmed cases and the scope of these anomalies have not been extensively documented. This review focuses on the magnitude of laboratory-confirmed congenital Zika virus cases among probable cases and describing the patterns of congenital anomalies allegedly caused by the Zika virus, information which will inform further research in this area. Methods: We conducted a literature search for English-language articles about congenital Zika virus infection using online electronic databases (PubMed/MEDLINE, POPLINE, Embase, Google Scholar, and Web of Knowledge). The search terms used were, “zika”, “pregnancy”, [year], “microcephaly”, “infants”, “children”, “neonates”, “foetuses”, “neural tube defect”, and “CNS manifestations” in different combinations. All articles reporting cases or case series between January 2015 and December 2016 were included. Data were entered into a Microsoft Excel database and analysed to obtain proportions of the confirmed cases and patterns of anomalies. Results: A total of 24 articles (11 case series, 9 case reports, and 4 others) were found to be eligible and included in this review. These articles reported 919 cases, with or without microcephaly, presumed to have congenital Zika virus infection. Of these cases, 884 (96.2%) had microcephaly. Of the 884 cases of microcephaly, 783 (88.6%) were tested for Zika virus infection, and 216 (27.6%; 95% confidence interval, 24.5% to 30.8%) were confirmed to be Zika virus-positive. In addition to microcephaly, other common abnormalities reported – out of 442 cases investigated – were calcifications of brain tissue (n=240, 54.3%), ventriculomegaly (n=93, 20.8%), cerebellar hypoplasia (n=52, 11.7%), and ocular manifestations (n=46, 10.4%). Conclusion: Based on the available literature, Zika virus infection during pregnancy might lead to a wide array of outcomes other than microcephaly. There is a need for more epidemiological studies in Zika-endemic areas, particularly in Africa, to ascertain the role of Zika virus in causing congenital neurological defects.