Zika-exposed Archives

Colombian infants exposed to Zika virus in the womb showed neurodevelopmental delays as toddlers, despite having “normal” brain imaging and head circumference at birth, a finding that underscores the importance of long-term neurodevelopmental follow-up for Zika-exposed infants.

“These infants had no evidence of Zika deficits or microcephaly at birth. Neurodevelopmental deficits, including declines in mobility and social cognition, emerged in their first year of life even as their head circumference remained normal,” says Sarah B. Mulkey, M.D. Ph.D., a fetal/neonatal neurologist at Children’s National Hospital and the study’s first author. “About one-third of these newborns who underwent postnatal head ultrasound had nonspecific imaging results, which we believe are the first published results finding a link between subtle brain injuries and impaired neuromotor development in Zika-exposed children.”

The multi-institutional research group led by Children’s National enrolled pregnant women in Atlántico Department, which hugs the Caribbean coast of Colombia, who had been exposed to Zika, and performed a series of fetal magnetic resonance images (MRI) and ultrasounds as their pregnancies progressed.

Even though their mothers had laboratory-confirmed Zika infections, 77 out of 82 of their offspring were born with no sign of congenital Zika syndrome, a constellation of birth defects that includes severe brain abnormalities, eye problems and congenital contractures, and 70 underwent additional testing of neurodevelopment during infancy. These apparently normal newborns were born between Aug. 1, 2016, and Nov. 30, 2017, at the height of the Zika epidemic, and had normal head circumference.

When they were 4 to 8 months or 9 to 18 months of age, the infants’ neurodevelopment was evaluated using two validated tools, the Warner Initial Developmental Evaluation of Adaptive and Functional Skills (a 50-item test of such skills as self-care, mobility, communication and social cognition) and the Alberta Infant Motor Scale (a motor examination of infants in prone, supine, sitting and standing positions). Some infants were assessed during each time point.

Women participating in the study were highly motivated, with 91% following up with appointments, even if it meant traveling hours by bus. In addition to Children’s National faculty traveling to Colombia to train staff how to administer the screening instruments, videotaped assessments, MRIs and ultrasounds were read, analyzed and scored at Children’s National. According to the study team, the U.S. scoring of Alberta Infant Motor Scale tests administered in Colombia is also unprecedented for a research study and offers the potential of remote scoring of infants’ motor skill maturity in regions of the world where pediatric specialists, like child neurologists, are lacking.

“Normally, neurodevelopment in infants and toddlers continues for years, building a sturdy neural network that they later use to carry out complex neurologic and cognitive functions as children enter school,” Dr. Mulkey adds. “Our findings underscore the recommendations by the Centers for Disease Control and Prevention (CDC) that all infants exposed to Zika in the womb undergo long-term follow-up, providing an opportunity to intervene earlier.”

An accompanying editorial by CDC staffers concurs, saying the study reported “intriguing data” that add “to the growing evidence of the need for long-term follow-up for all children with Zika virus exposure in utero to ensure they receive the recommended clinical evaluations even when no structural defects are identified at birth.”

In addition to Dr. Mulkey, study co-authors include Margarita Arroyave-Wessel, MPH, Dorothy I. Bulas, M.D., chief of Diagnostic Imaging and Radiology, JiJi Jiang, MS, Stephanie Russo, BS, Robert McCarter, ScD, research section head, design and biostatistics, Adré J. du Plessis, M.B.Ch.B., MPH, chief of the Division of Fetal and Transitional Medicine, and co-Senior Author, Roberta L. DeBiasi, MD, MS, chief of the Division of Pediatric Infectious Diseases, all of Children’s National; Colleen Peyton, PT, DPT, of Northwestern University; Yamil Fourzali, M.D., of Sabbag Radiologos, Barranquilla, Colombia; Michael E. Msall, M.D., of University of Chicago Comer Children’s Hospital; and co-Senior Author, Carlos Cure, M.D., BIOMELab, Barranquilla, Colombia.

Funding for the research described in this post was provided by the Thrasher Research Fund, the National Institutes of Health under award Nos. UL1TR001876 and KL2TR001877, and the Leadership Education in Neurodevelopmental and Related Disorders Training Program under grant HRSA/MCHB T73 MC11047.

In the midst of an unprecedented Zika crisis in Brazil, there were a few flickers of hope: Some babies appeared to be normal at birth, free of devastating birth defects that affected other Brazilian children exposed to the virus in utero. But according to a study published online July 8, 2019, in Nature Medicine and an accompanying commentary co-written by a Children’s National clinician-researcher, the reality for Zika-exposed infants is much more complicated.

Study authors led by Karin Nielsen-Saines at David Geffen UCLA School of Medicine followed 216 infants in Rio de Janeiro who had been exposed to the Zika virus during pregnancy, performing neurodevelopmental testing when the babies ranged in age from 7 to 32 months. These infants’ mothers had had Zika-related symptoms themselves, including rash.

Although many children had normal assessments, 29% scored below average in at least one domain of neurological development, including cognitive performance, fine and gross motor skills and expressive language, Sarah B. Mulkey, M.D., Ph.D., and a colleague write in a companion commentary published online by Nature Medicine July 29, 2019.

The study authors found progressively higher risks for developmental, hearing and eye abnormality depending on how early the pregnancy was at the time the infants were exposed. Because Zika virus has an affinity for immature neurons, even babies who were not born with microcephaly remained at continued risk for suffering abnormalities.

Of note, 24 of 49 (49%) infants who had abnormalities at birth went on to have normal test results in the second or third year of life. By contrast, 17 of 68 infants (25%) who had normal assessments at birth had below-average developmental testing or had abnormalities in hearing or vision by age 32 months.

“This work follows babies who were born in 2015 and 2016. It’s heartening that some babies born with abnormalities tested in the normal range later in life, though it’s unclear whether any specific interventions help to deliver these positive findings,” says Dr. Mulkey, a fetal–neonatal neurologist in the Division of Fetal and Transitional Medicine at Children’s National in Washington, D.C. “And it’s quite sobering that babies who appeared normal at birth went on to develop abnormalities due to that early Zika exposure.”

It’s unclear how closely the findings apply to the vast majority of U.S. women whose Zika infections were asymptomatic.

“This study adds to the growing body of research that argues in favor of ongoing follow-up for Zika-exposed children, even if their neurologic exams were reassuring at birth,” Dr. Mulkey adds. “As Zika-exposed children approach school age, it’s critical to better characterize the potential implications for the education system and public health.”

In addition to Dr. Mulkey, the perspective’s senior author, William J. Muller, Northwestern University, was the commentary’s lead author.

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