Researchers Urge More Monitoring for Babies Exposed to Zika

By Sherry Baker  @SherryNewsView
January 12, 2017

Babies born to moms infected with Zika may appear normal at first — but damage from the virus can show up months later.

Research from the Centers for Disease Control and Prevention (CDC) and the University of California at Los Angeles (UCLA) reveals babies who were exposed to Zika before birth may look perfectly normal — but in time, that assumption may turn out to be tragically wrong.

Parents and their baby’s doctor understandably breathe a sigh of relief when a newborn exposed to Zika in the womb shows no sign of microcephaly, the heartbreaking birth defect marked by a smaller than normal head and slowed brain growth. Microcephaly has been the most feared — and obvious — birth defect associated with the virus.


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But now it appears a child who was born seemingly healthy can experience slowed development and other signs of serious physical and mental problems months down the road. Understanding this possibility — and getting the word out to parents and, especially, pediatricians — is crucial, researchers say, so babies exposed to Zika pre-birth can be monitored closely throughout the first year of life. If and when problems show up, the children can receive follow-up care and specific treatments for Zika-linked health consequences, including vision and hearing problems and developmental delays.

A recent UCLA-led study of Zika-affected pregnancies in Rio de Janeiro, Brazil, found the virus caused more extensive and severe abnormalities than previously thought. In fact, nearly half — 46 percent — of 125 pregnant women infected with Zika either suffered miscarriages or gave birth to babies with birth defects. 

The research, published in the New England Journal of Medicine, found forty-two percent of infants born to the Zika-infected mothers were diagnosed with microcephaly. Some babies exposed pre-birth to the virus had brain lesions or brain calcifications seen in imaging studies, lesions in their eyes, hearing loss, feeding difficulties, and other complications. And the study found many of these Zika-caused birth defects were only detected weeks or six months after birth.

“This means that microcephaly is not the most common congenital defect from the Zika virus,” said Karin Nielsen, MD, the study’s senior author and professor of clinical pediatrics at UCLA’s David Geffen School of Medicine. “These are sobering results.”


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The babies in the study were first examined during early infancy, when “more subtle neurologic manifestations of disease are not identified,” the research team explained in their paper. Later examinations could reveal evidence of additional neurologic diseases that were not spotted in the early weeks and months of the babies’ lives, they concluded.

Research from the CDC, published in the Emerging Infectious Diseases Journal, may explain how seemingly healthy babies exposed to Zika could develop problems in the future — the virus may still be growing in their brains. 

The CDC research team found extremely high levels of Zika in the brains of infected babies who died after birth. They also discovered the virus can continue to replicate in the brain after birth, potentially causing a variety of damage to developing children over the course of weeks and months. For example, the researchers reported the case of one infant who seemed to have escaped the impact of Zika exposure before birth but developed neurological abnormalities six months later.

The researchers concluded periodic monitoring of infants who are exposed to Zika in the womb is needed to help spot and treat problems that may not develop until as long as a year after birth. 

Bottom line: While there’s no known cure for Zika and a vaccine is not yet available, women who are pregnant or may become pregnant should avoid areas where the Zika virus is being transmitted and practice safe sex or abstinence if their partner could have been exposed to the virus. And babies born to women who contracted Zika while pregnant need regular examinations by pediatricians so that any Zika-linked health problems can be identified and treated as early as possible.

Visit the CDC’s website for more information on Zika and pregnancy.


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March 31, 2020

Reviewed By:  

Christopher Nystuen, MD, MBA