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Maternal infection with Zika virus (ZIKV) is associated with a distinct pattern of birth defects, known as congenital Zika syndrome (CZS). In ZIKV-exposed children without CZS, it is often unclear whether they were protected from in utero infection and neurotropism. Early neurodevelopmental assessment is essential for detecting neurodevelopmental delays (NDDs) and prioritizing at-risk children for early intervention. We compared neurodevelopmental outcomes between ZIKV-exposed and unexposed children at 1, 3 and 4 years to assess exposure-associated NDD risk. A total of 384 mother–child dyads were enrolled during a period of active ZIKV transmission (2016–2017) in Grenada, West Indies. Exposure status was based on laboratory assessment of prenatal and postnatal maternal serum. Neurodevelopment was assessed using the Oxford Neurodevelopment Assessment, the NEPSY® Second Edition and Cardiff Vision Tests, at 12 (n = 66), 36 (n = 58) and 48 (n = 59) months, respectively. There were no differences in NDD rates or vision scores between ZIKV-exposed and unexposed children. Rates of microcephaly at birth (0.88% vs. 0.83%, p = 0.81), and childhood stunting and wasting did not differ between groups. Our results show that Grenadian ZIKV-exposed children, the majority of whom were without microcephaly, had similar neurodevelopmental outcomes to unexposed controls up to at least an age of 4 years.

Background While microcephaly is a significant adverse outcome of prenatal exposure to the Zika virus (ZIKV), subtle malformations of cortical development (MCD) have been observed in Zika-exposed children (ZEC), including delays in language, cognition, and motor domains, and visual acuity deficits. Interventions within the first 1,000 days of life can significantly improve developmental outcomes. This study examined a 12-week Responsive Caregiving Intervention on neurodevelopmental outcomes in 24-30-month-old ZEC. Methodology/Principal findings A randomized controlled trial was implemented in Grenada, West Indies using an existing ZIKV cohort surveillance study. When children in that study turned 24 months, baseline child neurodevelopmental measures and caregiver interviews were administered. Caregivers who agreed to participate in the 12-week Responsive Caregiving Intervention, implemented when children were 24–30 months of age, were randomly assigned to the Intervention or Waitlist Control group. Children in both groups were re-assessed on the neurodevelopmental measures post-intervention. Conclusions/Significance 233 children from the ZIKV surveillance study met inclusion criteria, of which n = 80 declined participation, n = 42 did not complete the Intervention, and n = 72 missed follow-up assessments given strict timelines in the study design. The final sample for analysis was N = 13 children in the Intervention group and N = 26 children in the Control group. A GEE model analysis showed significantly higher language (p = 0.021) and positive behaviour (p = 0.005) scores for children in the Intervention group compared to the Control group. The Intervention had a medium effect on child language (d = 0.66) and a large effect on positive behaviour (d = 0.83). A 12-week Responsive Caregiving Intervention Programme significantly improves language and positive behaviour scores in 30-month-old normocephalic children who were exposed to ZIKV in utero. The programme provides an option for mothers of ZIKV-exposed children who are seeking an evidence-based neurodevelopmental intervention regardless of known impact of the virus on cortical formation. Trial registration The study was registered with clinicaltrials.gov (NCT04697147). Author summary The relationship between Zika virus exposure during pregnancy and microcephaly (abnormally small head size) in infants is well known. Prenatal Zika virus exposure can also cause more subtle impacts in infant language, cognition, and motor function, and visual acuity, even in the absence of microcephaly. Interventions in the first 1,000 days of life can significantly improve these outcomes in at-risk children. Few studies have been carried out with the aim of improving neurodevelopment in Zika-exposed children. The present study utilized a randomized controlled trial to examine the impact of a 12-week Intervention on neurodevelopmental outcomes in 24-30-month-old Zika-exposed children. Analysis showed significantly higher language and positive behaviour scores among children in the Intervention group compared to children in the Control group. The Intervention used in this study is relatively low-cost and easy to implement. The application of interventions from the global early child development field has implications for governments, policy makers, public health officials, and parents of Zika-exposed children who are seeking effective interventions to mitigate the risk of neurodevelopment delays in those children. The fact that these much-needed interventions already exist and can be rolled out relatively quickly and effectively is encouraging.