Zika’s Undetected Long-Term Impact on Children

A new study suggests the need for long-term neurodevelopmental monitoring for all infants with Zika virus exposure to ascertain the impact of the virus as the infected child ages.

In this study published in JAMA on January 6, 2020, infants exposed to Zika virus in the womb showed neurodevelopmental delays as toddlers, despite having "normal" brain imaging and head circumference at birth.

Sarah B. Mulkey, M.D. Ph.D., a fetal/neonatal neurologist at Children's National Hospital in Washington, D.C., and the study's first author said in a related press release, ‘about one-third of these newborns who underwent postnatal head ultrasound had nonspecific imaging results.’

‘We believe these are the first published results finding a link between subtle brain injuries and impaired neuromotor development in Zika-exposed children.’

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 (CZS), which is a group of birth defects that includes severe brain abnormalities, eye problems, and congenital contractures.

Of the 77 Colombian infants included in this cohort study, 70 (91%) had no CZS and underwent neurodevelopmental assessments.

When the 70 infants were 4 to 8 months or 9 to 18 months of age, their neurodevelopment was evaluated using validated tools, the Warner Initial Developmental Evaluation of Adaptive and Functional Skills and the Alberta Infant Motor Scale. Some infants were assessed during each time point.

"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 added.

"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."

The CDC developed guidance for healthcare providers treating babies with congenital Zika syndrome in 2017. The tests and screenings newborns might receive in the first month of life include the following:

• A comprehensive physical exam. Your baby’s healthcare provider measures your baby’s weight, length, and head circumference (the distance around your baby’s head). Your baby’s skin, head, and neck, heart, lungs, abdomen, genitals, muscles, bones, and alertness and responsiveness are examined.
• A test for Zika virus infection. Your baby’s healthcare provider may take small samples of your baby’s blood and urine. A negative test result does not always indicate that your baby was not infected with the Zika virus. However, a positive test could confirm the Zika virus infection and helps your baby’s healthcare provider decide how best to care for your baby. Your baby’s healthcare provider may also test your baby’s cerebrospinal fluid (the liquid that covers the brain and spinal cord) for the Zika virus.
• A head ultrasound to check your baby’s brain development. The baby’s healthcare provider may order a ultrasound (using a machine that takes pictures of your baby’s brain). Sometimes, your doctor may refer your baby to see a specialist to have more advanced pictures, like magnetic resonance images (MRI), taken of his or her brain. These tests and physical exams help tell your healthcare providers if your baby has problems with brain development.
• An ophthalmology (eye) exam. Zika virus can cause damage to your baby’s eyes that could affect his or her vision. An ophthalmologist (eye doctor) may use special equipment to look carefully at your baby’s eyes to examine their structure and check for abnormalities. Your doctor may use eye drops to temporarily enlarge your baby’s pupils (the dark circle in the middle of the colored part of the eye). This allows your doctor to see inside the eyes.
• A hearing test. Your baby’s healthcare provider may do an auditory brainstem response (ABR) test during the first hospital stay or soon after you leave the hospital. This is a special hearing test that checks the brain’s response to sound. Small, painless stickers that can measure hearing are placed on your baby’s head and connected by wires to a computer. Earphones are placed over your baby’s ears. As sounds are made through the earphones, the stickers on your baby’s head send information to the computer about how your baby’s brain responds to the sounds.

An accompanying editorial published in JAMA by CDC doctors concurs with this study’s findings.

These CDC researchers said ‘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 the United States, more than 7,400 pregnancies with laboratory evidence of confirmed or possible Zika virus infection were identified and included in the national surveillance network, the US Zika Pregnancy and Infant Registry, during the Zika virus outbreak in the Region of the Americas from 2015 to 2017.

These pregnancies included those completed from December 1, 2015, through March 31, 2018, meaning the children from these pregnancies ranged in age from 18 months to nearly 4 years by the fall of 2019. 

Although between 5 - 10 percent of these children have received a diagnosis of serious defects of the brain or eye, including microcephaly, many of them have not undergone the recommended postnatal brain imaging and ophthalmological examinations to fully identify these health problems.

Some infants with a standard head circumference measurement at birth may have an underlying brain and/or eye defects, said these CDC doctors.

This is important news since the state of Florida reported 36 cases of Zika fever in individuals with travel history to a country or area experiencing Zika virus activity.

Furthermore, the Florida health department is monitoring a total of 23 pregnant women diagnosed with Zika during 2019.

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.

No conflicts of interest were disclosed.

Zika vaccine and condition news is published by Zika News.