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Zika-Associated Birth Defects Initiated While Pregnant

January 23, 2022 • 10:19 am CST
(Zika News)

According to a new estimate published in U.S. CDC's Morbidity and Mortality Weekly Report (MMWR) on January 21, 2022, about 5% of U.S. infants born to mothers with a confirmed or possible Zika virus infection during pregnancy had a Zika-associated brain or eye defect.

This new study reconfirms a Zika virus infection during pregnancy can cause serious congenital disabilities of the brain and eyes, including intracranial calcifications, cerebral or cortical atrophy, chorioretinal abnormalities, and optic nerve abnormalities.

The frequency of these Zika-associated brain and eye defects, based on data from the U.S. Zika Pregnancy and Infant Registry (USZPIR), has been previously reported in aggregate.

Among 6,799 live-born infants in USZPIR born during December 1, 2015–March 31, 2018, 4.6% had any Zika-associated birth defect.

In a subgroup of pregnancies with a positive nucleic acid amplification test for Zika virus infection, the percentage was 6.1% of live-born infants.

The brain and eye defects most frequently reported included microcephaly, corpus callosum abnormalities, intracranial calcification, abnormal cortical gyral patterns, ventriculomegaly, cerebral or cortical atrophy, chorioretinal abnormalities, and optic nerve abnormalities.

About one-third of infants with any Zika-associated congenital disability had more than one defect reported.

And these brain and eye defects in an infant might prompt suspicion of prenatal Zika virus infection.

Moreover, among 325 pregnancies with laboratory evidence of confirmed or possible Zika virus infection that resulted in a pregnancy loss, 4% of fetuses had any reported Zika-associated congenital disability (C Moore, CDC, unpublished data, 2022).

These findings can help target surveillance efforts to the most common brain and eye defects associated with Zika virus infection during pregnancy should a Zika virus outbreak reemerge, and might signal the reemergence of Zika virus, particularly in geographic regions without ongoing comprehensive Zika virus surveillance.

The findings in this report are subject to at least five limitations. First, these data are based on information abstracted from medical records.

Although CDC provided specific guidance for evaluating all infants born from pregnancies with possible Zika virus exposure during pregnancy, these evaluations might not have been feasible, were not always conducted, or were not found in records.

Corresponding author: Nicole M. Roth, [email protected].