New research helps better understand risks associated with prenatal Zika virus infections

About one-third of children born to mothers infected with the Zika virus during pregnancy have at least one abnormality consistent with congenital Zika syndrome in the first few years of life, new research shows.

The findings – based on the pooled analysis of 13 studies looking at pediatric outcomes among more than 1,500 Zika virus-affected pregnancies during the 2015-2017 outbreak in Brazil – improve our understanding of the risks associated with prenatal infections by the Zika virus, with important implications for public health.

Following the emergence of an outbreak of microcephaly in Brazil in 2015, the possibility of an association between increased Zika virus transmission and potential birth defects emerged.

Although studies have examined potential adverse pregnancy outcomes following infection, small sample sizes, high variability between estimates, and reliance on routine surveillance data have limited our understanding of the true extent of this risk. .

In this study, the team – made up of researchers from 26 institutions in Brazil in collaboration with the London School of Hygiene & Tropical Medicine (LSHTM) and the University of California, Los Angeles – analyzed data on the offspring of 1,548 pregnant women from 13 cohort studies in the Zika Brazilian Cohorts Consortium. These data include the four regions of Brazil affected by the epidemic between 2015 and 2017, with laboratory-confirmed prenatal infection using genetic testing and potential adverse effects assessed at the individual level and harmonized between studies.

Overall, the most frequently observed manifestations of congenital Zika syndrome in children included functional neurological disorders, neuroimaging abnormalities, hearing and vision alterations, and microcephaly. The results provide evidence that congenital anomalies were more likely to present in isolation, with less than 0.1% of exposed offspring presenting with two anomalies simultaneously.

The risk of offspring having microcephaly – a neurological condition in which the baby’s head is smaller than expected for their age and gender – was found to be around 2.6% at birth or when first rating, increasing to 4.0% during the early preschool years. This risk remained relatively constant across all study sites, with no apparent variation by socioeconomic conditions.

The research is published in The Lancet Regional Health – Americas.

These findings underscore the importance of having multidisciplinary health teams available near the time of birth to assess children with prenatal exposure to Zika virus exposure and to refer them, as needed, for specialized follow-up care. who can provide support for known disabilities and diagnosis of late manifestations.”

Professor Ricardo Arraes de Alencar Ximenes, lead author, Federal University of Pernambuco in Brazil

Study co-author and Associate Professor of Epidemiology at LSHTM, Dr Elizabeth Brickley, also said: “These results underscore the continued need to develop a safe and effective vaccine to prevent Zika virus infections during pregnancy. “While gaps in population-level immunity to the virus persist, the threat of Zika virus re-emergence remains a public health concern.”

For the future, the researchers point out that additional studies with longer follow-up times will be necessary. Potential avenues of investigation include assessing the risk of hospitalization and death in children with microcephaly as they age, and in those without microcephaly, examining the risks of other complications, such as those related to behavioral or neuropsychomotor development.