Fetal Central Nervous System Anomalies According to RT-PCR and Trimester of Maternal Infection with ZIKV. A Prospective Study

Background: In October of 2015, an epidemic of Zika began in Colombia's geographic areas with a high population of mosquitoes of the genus Aedes. Our aim was to describe the outcome of fetuses of symptomatic pregnant women who were tested with RT-PCR for ZIKV according to trimester of infection. Methods: Symptomatic women were tested with RT-PCR for ZIKV and followed prospectively by obstetricians and high-risk maternal-fetal medicine specialists, using detailed anatomic ultrasound and neurosonography to detect fetal structural anomalies of the central nervous system (CNS) according to trimester of infection. Findings: 115 symptomatic women with a positive RT-PCR and 56 with a negative RT-PCR were enrolled in the study; CNS compromise of the fetus occurred in 24% and 20%, respectively (p=0.398). When symptomatic ZIKV positive women were categorized by trimester of infection, CNS anomalies were present in 38% of first-trimester infections, compared to 21% and 10% in second and third-trimester infections (p=0.012). Including all trimesters, neuronal migration disorders were the most frequent anomaly of the CNS (15%), followed by microcephaly (13%). Interpretation: Prevalence of CNS anomalies were similar between symptomatic RT-PCR ZIKV positive and negative pregnant women suggesting a high rate of false-negative results with RT-PCR. First-trimester infections were more frequent and severe compared to second and third-trimester infections in exposed fetuses. The prevalence of CNS anomalies was higher than previously reported in the literature, possibly due to fetal-ultrasound assessments' quality and expertise. Migrational disorders were the most frequently observed anomaly of the CNS, followed by microcephaly. Funding: Grants from the Universidad Industrial de Santander (UIS), and the Epidemiology Research Center at UIS, supported this study. Conflict of Interest: We declare no competing interests. Ethical Approval: The Committee on Ethics and Research from the Universidad Industrial de Santander and participating centers approved the study. All pregnant women signed informed consent for participation in this study.