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Most Babies Exposed to Zika Virus have Normal Brain Development

Remember the Zika virus scare, and how we were led to believe thousands of babies were going to be born with birth defects, including terrible brain abnormalities? Well, reality is showing a very different picture.

More than 100 U.S. infants were born with Zika-associated birth defects; some of these had mild brain abnormalities that were not detected by prenatal ultrasounds. But the vast majority of U.S. infants exposed prenatally to the Zika virus were apparently normal at birth, a new study shows.

“A combination of prenatal MRI and [ultrasound] was able to detect Zika-related brain abnormalities during pregnancy, giving families timely information to prepare for the potential complex care needs of these infants,” says Dr Sarah B. Mulkey, a fetal-neonatal neurologist at Children’s National Health System and lead author of the study published in JAMA Pediatrics.

As of mid-October 2018, nearly 2,500 pregnant women in the U.S. had laboratory confirmed Zika infection, and about 2,400 of them had given birth, according to the Centers for Disease Control and Prevention (CDC). While more than 100 U.S. infants were born with Zika-associated birth defects, the vast majority of Zika-exposed U.S. infants were apparently normal at birth. The sequential neuroimaging study Dr Mulkey leads seeks to determine the spectrum of brain findings in infants exposed to Zika in the womb using both ultrasound and MRI before and after birth.

The international research team enrolled 82 women in the study between June 2016 and June 2017. All of the women had been exposed to Zika during pregnancy. All women received fetal MRIs and ultrasound during the second and/or third trimester of pregnancy. After the infants were born, the children received brain MRI and cranial ultrasound. Blood samples from both mothers and babies were tested for Zika using polymerase chain reaction and serology.

Fetal MRI was able to discern Zika-related brain damage as early as 18 weeks gestation and picked up significant fetal brain abnormalities not fully appreciated in ultrasound imaging. In one case, the ultrasound remained normal while fetal MRI alone detected brain abnormalities. Three fetuses (4 per cent) had severe fetal brain abnormalities consistent with Zika infection.

Seventy-five infants were born at term. One pregnancy was terminated at 23 weeks. One fetus with normal imaging died during pregnancy. One baby who was born with significant brain abnormalities died at age 3 days.

13 per cent of Zika-exposed infants had mild brain abnormalities detected by MRI after birth. Other abnormalities were detected by postnatal cranial ultrasound in 37 per cent of the infants.

“Sequential neuroimaging revealed that the majority of Zika-exposed fetuses had normal brain development. Tragically, in a small number of pregnancies, Zika-related brain abnormalities were quite severe,” Dr Mulkey adds. “Our data support the CDC’s recommendation that cranial ultrasounds be performed after Zika-exposed babies are born. In addition, there is clearly a need to follow these babies over time to gauge whether the brain anomalies we see in imaging affects language, motor and social skills.”

Medical Xpress. November 26. JAMA Pediatrics. November 26.

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