Babies from Colombia who
were born healthy after being exposed to the Zika virus in the womb showed
signs of neurodevelopmental delays by 18 months of age, a small study finds.
The work supports long-term follow-up of babies whose mothers had the viral infection
during pregnancy, the researchers say.

As a group, the 70 babies exposed to Zika didn’t hit certain developmental milestones for movement and social interaction around the times expected for healthy, nonexposed babies of the same age, researchers report January 6 in JAMA Pediatrics.

Overall, the children lagged
in mobility skills such as rolling over or sitting up, and in play skills like
peekaboo and searching for an object that has dropped out of sight, says Sarah
Mulkey, a fetal neonatal neurologist at Children’s National Hospital in
Washington, D.C. Within the group, some children developed as expected, some showed
obvious development delays, and some showed more subtle delays that caregivers
might not have noticed.

Because there was
variability between individuals, “looking at a population enables one to see
overall trends,” says neurologist Ken Tyler of the University of Colorado
School of Medicine in Aurora, who was not involved in the research. “We need to
aggressively follow all children whose mothers were exposed to Zika during
pregnancy to understand the nature of their neurological delays.”

Mulkey and her team, including researchers in Colombia, assessed babies
born between August 1, 2016, and November 30, 2017 — during and after the Zika
epidemic that gripped Brazil, Colombia and other countries in the Americas
(SN: 10/30/17). About five to 10
percent of babies born to Zika-exposed mothers in the United States and U.S.
territories had severe birth defects, including an abnormally small head and
brain damage. But the large majority weren’t born with these defects.

A 2018 study of Zika-exposed babies from U.S. territories up to their first birthday, including some with
abnormalities apparent at birth, reported a range of health problems possibly
due to the virus (SN: 8/7/18). 

The new study followed the
70 babies for a year and a half, assessing them at least once between the ages
of 4 and 18 months old. The babies had normal fetal development and head
circumference. But the results from the two neurodevelopmental tests — a questionnaire and an observational exam — suggest it’s possible that problems may not arise
until later.

“We
are still learning exactly how Zika exposure can affect a developing fetus and
beyond,” says neurologist Nassim Zecavati of Georgetown University School of
Medicine in Washington D.C., who was not involved in the research. More work is
needed to determine the reasons for the delays in this group of children, and
whether it’s a temporary decline, she says.

The neurodevelopmental
differences found in the children can be addressed with physical and
occupational therapy, Mulkey says. Her team will follow this group until they
are 5 years old. “We don’t yet know the future of how these children are going
to develop long-term,” she says.