More Than Microcephaly: Congenital Zika Syndrome

Laura A. Stokowski, RN, MS; William B. Dobyns, MD


September 21, 2016

In This Article

The Story Isn't Over

Medscape: We have often heard people say that Zika has been around for decades. If these neurologic disorders are really related to the Zika virus, why haven't we heard about them before?

Dr Dobyns: At first there was speculation that the Zika virus in Brazil was a mutation, and that the African and Asian forms of the Zika virus didn't cause neurodevelopmental disorders. On the basis of laboratory studies, we now know that isn't true. Consider CMV. In any given population here in America, only about 15% of women of childbearing age have never been infected with CMV so don't have antibodies, leaving them vulnerable to infection.

The Zika virus originated in Africa and then traveled to South Asia, Indonesia, Polynesia, and Brazil, as far as virologists and epidemiologists can tell. It has been endemic in Africa for hundreds of years, if not longer. [Editor's note: A timeline of Zika's migration from Africa to South America can be found here.] As with CMV, the majority of women will have been infected and will have developed antibodies to the Zika virus. Thus, only a small percentage is at risk of having a child with congenital Zika syndrome. In these countries, which have perhaps the world's worst health infrastructures, it is not surprising that no connection is made between the occasional baby with microcephaly and the Zika virus. A retrospective analysis[11] suggests that there was, in fact, an increase in congenital cerebral malformations and dysfunction in fetuses and newborns in French Polynesia after an epidemic of Zika virus.

Brazil has a huge Zika-naïve population, as does Colombia, Central America, Haiti, Puerto Rico, and the southeastern United States.

In the southeast United States, people are often indoors, so mosquito exposure is not as great in Miami as it is in Brazil, where they don't have much air conditioning and the windows are open. The rate of Zika infection among pregnant women is likely to be lower, but we're going to see it.

Medscape: Are there unidentified children out there with a milder condition?

Dr Dobyns: If you are asking whether there is a less severe but harder to diagnosis Zika-related developmental disorder, I think the answer is yes. All of the new data show that less severely affected babies are being seen.

What we have seen so far is just the tip of the iceberg, but we don't know what the rest of the iceberg looks like. We don't know the full story.

It is likely that some children with congenital Zika syndrome have a normal head size, at least at the time of birth. Therefore, the number of affected infants is likely to be even larger than has been currently suggested. With our greater experience now with CMV, we know that there are more subtle effects that can present later. With Zika, we just don't know yet.

Medscape: What else should clinicians know?

Dr Dobyns: The real key is that this is a recognizable syndrome, although there may well be less severe forms that are not yet recognized. What we have seen so far is just the tip of the iceberg, but we don't know what the rest of the iceberg looks like. We don't know the full story.

We need to get away from calling this microcephaly. That isn't appropriate anymore and it has been a real problem. Politicians will pick this up and say, "Well, the baby's head size might be a little bit smaller but he or she will be otherwise fine." If we don't use a more specific designation, we leave it open to that sort of misinterpretation. This needs to be called congenital Zika syndrome.


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