WASHINGTON – Evidence continues to mount that infants born to moms infected with Zika virus during pregnancy can have neurodevelopmental abnormalities as they age even if they showed no defects at birth, based on follow-up of 890 Colombian children tracked by epidemiologists from the U.S. Centers for Disease Control and Prevention.
Among the 890 neonates born to mothers apparently infected with Zika during pregnancy and followed for up to 2 years, 40 of the 852 (5%) without a detectable birth defect at delivery went on to show some type of neurodevelopmental sequelae during up to 24 months of age,, said at an annual scientific meeting on infectious diseases.
In addition, among the children without birth defects at delivery who received follow-up examinations out to about 2 years, the incidence of “alerts” for possible neurodevelopmental issues was 15%-20% for each of the four domains studied (gross motor, fine motor, hearing and language, and personal and social functions), said Dr. Honein, an epidemiologist and chief of the birth defects branch of the CDC. In contrast, 17 of the 38 children (45%) followed who had identifiable birth defects at delivery also showed neurodevelopmental abnormalities when reexamined as long as 2 years after birth. These possible neurodevelopmental abnormalities, designated as alerts, were identified in comparison with a contemporaneous cohort of children born to uninfected mothers in the same regions of Colombia and assessed by the CDC researchers.
This cohort of children born to mothers who became infected with Zika virus during the 2016 Colombian epidemic will not undergo any planned, additional follow-up beyond the initial 2 years, Dr. Honein noted.
The findings she reported were consistent with observations from a much smaller cohort of 70 infants born to Colombian mothers infected with Zika virus while pregnant who had a normal head circumference and a normal clinical examination at delivery. When assessed once or twice 4-18 months after birth, these 70 infants showed an overall greater than one standard deviation (z-score) drop in their scores on the Warner Initial Developmental Evaluation of Adaptive and Functional Skills () by 12 months after birth and continuing out to 18 months, said , a fetal-neonatal neurologist at Children’s National Health System in Washington. These deficits were especially pronounced in the mobility and social cognition domains of the four-domain WIDEA metric. The social cognition domain is an important predictor of later problems with executive function and other neurologic disorders, Dr. Mulkey said while reporting her findings in a separate talk at the meeting. She acknowledged that the analysis was flawed by comparing the WIDEA outcomes of the Zika virus–exposed children to healthy children from either inner-city Chicago or Canada. Dr. Mulkey said that she and her associates plan to characterize a population of Zika virus–unexposed children in Colombia to use for future comparisons.
The study reported by Dr. Honein involved an enhanced surveillance program launched by the CDC in 2016 in three regions of Colombia and included 1,190 pregnancies accompanied by Zika symptoms in the mother and with a reported pregnancy outcome, including 1,185 live births. Nearly half of the Zika infections occurred during the first trimester, and 34% occurred during the second trimester. However, fewer than a third of the pregnant women underwent some type of laboratory testing to confirm their infection, either by serology or by a DNA-based assay, and of these 28% had a positive finding. Dr. Honein cautioned that many of the specimens that tested negative for Zika virus may have been false negatives.
The birth defects identified among the infants born from an apparently affected pregnancy included brain abnormalities, eye anomalies, and microcephaly, with 5% of the 1,185 live births showing one or more of these outcomes. The neurodevelopmental deficits identified during follow-up of 890 of the children out to 2 years included seizures; abnormalities of tone, movement, or swallowing; and impairments of vision or hearing.