Neurodevelopment in normocephalic children with and without prenatal Zika virus exposure
Karen Blackmon1,2, Roberta Evans2, Michelle Fernandes3,4
1Department of Psychiatry and Psychology, Mayo Clinic, Jacksonville, Florida, USA blackmon.karen@mayo.edu.
Insights
Zika virus (ZIKV) exposure did not affect overall neurodevelopment in children with normal head growth. However, ZIKV-exposed infants showed visual deficits, suggesting selective vulnerability of the visual system.
Area of Science:
- Neuroscience
- Virology
- Developmental Pediatrics
Background:
- Zika virus (ZIKV) targets neural stem cells, potentially impacting brain development.
- Most ZIKV-exposed children appear neurologically unaffected, raising questions about protection versus subtle pathology.
- Understanding ZIKV's neurodevelopmental impact is crucial for affected populations.
Purpose of the Study:
- To compare neurodevelopmental outcomes in normocephalic ZIKV-exposed children versus unexposed controls.
- To identify subtle neurological or developmental effects of prenatal ZIKV exposure.
- To assess the vulnerability of specific brain systems to ZIKV.
Main Methods:
- A prospective cohort study involving 384 mother-child pairs in Grenada during ZIKV transmission.
- Neurodevelopmental assessment using the INTERGROWTH-21st Neurodevelopment Assessment (INTER-NDA) and Cardiff Vision Tests in 131 children (22-30 months).
- Child exposure status determined by maternal serum laboratory assessment; assessors were masked to exposure status.
Main Results:
- No group differences in sociodemographics were observed.
- ZIKV-exposed infants (n=68) showed deficits in visual acuity (31%) and contrast sensitivity (23%) compared to unexposed controls (n=63).
- No cognitive, motor, language, or behavioral delays were found in ZIKV-exposed children.
Conclusions:
- Overall neurodevelopment appears unaffected in ZIKV-exposed children with normal head circumference and growth.
- The visual system demonstrates selective vulnerability to ZIKV exposure.
- Routine vision testing is recommended for ZIKV-exposed children by age 3.
Objective:
Zika virus (ZIKV) targets neural stem cells in the developing brain. However, the majority of ZIKV-exposed children are born without apparent neurological manifestations. It remains unclear if these children were protected from ZIKV neurotropism or if they harbour subtle pathology that is disruptive to brain development. We assess this by comparing neurodevelopmental outcomes in normocephalic ZIKV-exposed children relative to a parallel control group of unexposed controls.
Design:
Cohort study.
Setting:
Public health centres in Grenada, West Indies.
Patients:
384 mother-child pairs were enrolled during a period of active ZIKV transmission (April 2016-March 2017) and prospectively followed up to 30 months. Child exposure status was based on laboratory assessment of prenatal and postnatal maternal serum.
Main Outcome Measures:
The INTERGROWTH-21st Neurodevelopment Assessment (INTER-NDA) package and Cardiff Vision Tests, administered and scored by research staff masked to child's exposure status.
Results:
A total of 131 normocephalic ZIKV exposed (n=68) and unexposed (n=63) children were assessed between 22 and 30 months of age. Approximately half of these children completed vision testing. There were no group differences in sociodemographics. Deficits in visual acuity (31%) and contrast sensitivity (23%) were apparent in the ZIKV-exposed infants in the absence of cognitive, motor, language or behavioural delays.
Conclusions:
Overall neurodevelopment is likely to be unaffected in ZIKV-exposed children with normal head circumference at birth and normal head growth in the first 2 years of life. However, the visual system may be selectively vulnerable, which indicates the need for vision testing by 3 years of age.
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