Infectious Disease Expert: ‘So Much We Don’t Know’ About Effects of Zika in Pregnancy

By Lauretta Brown | June 29, 2016 | 10:31am EDT
Lara, who is less than 3 months old and was born with microcephaly, is examined by a neurologist in Brazil. (Felipe Dana/The Associated Press)

( – Dr. Jeanne Sheffield, an expert in pregnancy and infectious disease and the director of maternal-fetal medicine at Johns Hopkins Hospital, stressed that “there is so much we don’t know” about the effects of the Zika virus in pregnancy during a Capitol Hill briefing Tuesday on child health during pregnancy.

“There is so much we don’t know,” Sheffield said of the effects of Zika on mother and child during pregnancy, “we don’t know the true incidence among pregnant women.”

“We have no idea of you take a thousand women that happen to be pregnant how many of them are going to turn positive for Zika over the course of their pregnancy,” she added. “Then if a woman does turn positive during the pregnancy, we right now have no idea how many babies are going to get infected.

“We don’t know what the transmission risk truly is. All we have is preliminary stuff, so we are in desperate need, because that’s what my patients want to know,” she emphasized. “They come to me, and they say, what are my chances? I’ve traveled to Puerto Rico. What are my chances of getting infected. What are my chances if I get infected of infecting my kid?

She added that if a child is infected and tests positive for Zika, “how many of them are actually going to one, have symptoms and two, what are the long term consequences? What are these kids who look absolutely normal at birth - everything is perfect at birth - are they going to be developmentally delayed at age two or age five? We have no idea.”

Dr. Catherine Y. Spong, acting director of the National Institute of Child Health and Human Development (NIHCD), also emphasized the need for more information on the Zika virus in pregnancy, citing a recently launched multi-country study of pregnant women in Puerto Rico, Brazil, and other areas that are experiencing active local transmission of the virus that she hopes will yield the much needed information. The NIHCD is funding and conducting the study along with the National Institute of Environmental Health Sciences (NIEHS).

“We need a lot of information about Zika, and some of that we can best get through animal models, and some of that we can only get through a large cohort study, so both are absolutely essential,” Spong said. “We need to understand and be able to counsel the women who we see in our practices, what is the risk in pregnancy?”

Sheffield also discussed the things that are known about Zika and birth defects linked to the virus, such as microcephaly.

“The last few months we’re starting to get true basic science and translational data saying that yes, this virus does target specific neural cells and yes, this virus does target the placenta and infect the placenta and then goes over to the fetus,” Sheffield said.

“We now know that there is truly biologic link, and the CDC came out a couple months ago and said yes, there is a definite link between the two,” she said.

“These brains are very abnormal to look at,” Sheffield said of the infants infected with the Zika virus who have microcephaly.

“There’s also really impressive eye findings,” she added, “so we’ve now got the ophthalmologists involved and the neurologists involved in this research, because there’s very abnormal eye findings in some of these infants also.”

Sheffield also emphasized that the birth defects found in Zika infected infants were “not just a small head” characteristic of microcephaly but also “growth restrictions, so they weren’t growing normally. It was calcifications of the brain. It was other central nervous system abnormalities, fluid abnormalities, multiple things we’re seeing, so again not just a small head.”

Another alarming finding Dr. Sheffield mentioned was the transmission of the virus from mother to infant in all trimesters of pregnancy.

“We’re so used to viruses affecting infants early in pregnancy causing disease, and then if you get infected later on in pregnancy, maybe it’s not as bad,” she said, “but we know that even though it may be worse in the first part of pregnancy, we do know that there are babies born to moms that were infected in the third trimester that still have some abnormalities, and so we’re having to counsel women that it’s going across everything.”

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