Zika Has More Effects on Fetuses Than Just Microcephaly, Scientists Warn in Study

It can be difficult for nonpregnant Miamians to gauge how much they should really worry about Zika. On one hand, a new University of Florida study predicts South Florida's outbreak should top out at 400 locally transmitted cases and end by the winter.

But another new study paints a more dire picture of the disease's effects. The study, released yesterday in the peer-reviewed scientific journal Radiology, warns that babies born after being exposed to the Zika virus could still develop long-term brain abnormalities even if they aren't born with microcephaly or obvious brain defects at birth.

For state and local government officials — who have already been accused of trying to use the outbreak to score political points — it's a sobering thought that the virus could harm more children than previously thought.

According to the study, conducted by multiple scientists at Brazilian universities and at least one from Harvard, it's possible that children exposed to Zika in utero may be born with normal-size heads but still suffer from a host of internal conditions. Among other groups studied, scientists monitored 26 U.S. fetuses that had been exposed to Zika — though 23 were born with small heads, three babies were born without microcephaly but with many other brain defects.

It is "notable that the three fetuses with head circumference in the normal range at birth showed severe ventriculomegaly, which we presume was due to the enlarged, obstructed ventricles," the study says, referring to a condition that causes blood vessels to swell.

The children were also born with "calcifications" in various regions of the brain, including the thalamus, basal ganglia, and brain stem. 

Among other deformities, "abnormalities of the brain stem were identified," the study says. "The pons was often thin and atrophic. There was frequently a kink seen at the pontomedullary junction," a major cluster of nerve endings at the bottom of the brain.

Though it's long been known that Zika causes various brain abnormalities — especially because "microcephaly" is typically a symptom of other brain defects — the study sheds a light on exactly what regions of the brain the virus effects before birth and what scientists should watch for when examining fetuses in Zika-affected regions.

But frighteningly, the findings suggest that even if children exposed to the virus aren't born with obvious problems from day one, they might develop issues years down the line. The study shows that regions of the thalamus, responsible for regulating sleep and most of the body's sensory functions, could develop clumps of calcium over time.

Zika-affected babies also developed calcifications in the outer layer of the brain (the cortex), which plays a crucial role in learning and brain development.

The New York Times reports that although the study is scary for parents in the Latin American countries currently ravaged by Zika, the results could help doctors diagnose Zika earlier and figure out exactly what areas of the brain the virus affects.

For now, however, doctors say the major thing they've gleaned from the study is that, even if a child exposed to Zika isn't born with obvious deformities, it will be crucial to monitor those children for years to see if they develop learning or brain-growth issues.

"It’s key to realize that Zika is more than microcephaly, that there’s a number of other abnormalities as they’ve shown in this paper, and its effects are going to be even more broad," Dr. Catherine Y. Spong, acting director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, told the Times. "It’s going to be essential to follow them to look at their development, to look at their ability to learn, to look at hearing problems, balance problems, behavior problems, all those issues, to make sure that we don’t miss anyone.”