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New Zika Virus Findings on Birth Defects Revealed

The physicians also note that more work needs to be done to address “the limitations of current diagnostic testing” for Zika and related complications, an issue that is highlighted by other recent findings. In the same issue of NEJM, for example, a study of a cohort of pregnant women (125 completed pregnancies) from Rio de Janeiro with laboratory-confirmed Zika virus found that among 117 live infants born to 116 women, 42% were born with “grossly abnormal clinical or brain imaging findings or both,” and 4 had microcephaly. In all, 55% of pregnancies had adverse outcomes following maternal infection in the first trimester, 52% following infection in the second trimester, and 29% following infection in the third trimester.
Additionally, a case report, also published in NEJM (on December 7), noted that in a Colombian woman with laboratory-confirmed Zika, the fetus displayed no “brain abnormalities” on scans obtained at 12 and 15 weeks gestation, and that neurosonography performed at 20, 24, and 29 weeks revealed “bilateral mild ventriculomegaly and a shortened corpus callosum.” After the baby was delivered at 37 weeks gestation (due to suspected growth restriction), “postnatal ultrasonography and MRI studies confirmed the presence of microcephaly with a thinned corpus callosum and brain atrophy with parenchymal calcifications,” the authors of the report note.
“We would hypothesize that the persistent viremia that was detected in the mother could be the result of viral replication in the fetus or placenta, which thus acts as a reservoir,” they continue. “[Therefore], persistent [Zika virus RNA] in maternal serum could be a sign of fetal infection, and thus the fetus may play a role in persistent maternal viremia.”
Based on findings such as these, the CDC researchers note in their NEJM commentary that, “even in the absence of definitive testing, infants with possible congenital [Zika virus] infection will need to be followed carefully in infancy and childhood to identify any related health consequences or disabilities and to ensure that they are receiving the best available services.”
Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.
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