Zika warning marks alarming shift in CDC mindset
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Yesterday, Florida governor, Rick Scott, reported that ten additional cases of Zika were in all likelihood, acquired locally. This followed Friday’s announcement that the emerging virus had been spread from person-to-person by mosquitoes in Miami.

The advisory was somewhat surprising, given that the Centers for Disease Control and Prevention director, Dr. Thomas Frieden said as recently as Friday, that local transmission was not enough to warrant advising against travel, and that he expected additional cases to emerge.

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Nonetheless, the CDC advisory was indeed issued, and it contained an additional measure that was unique. All pregnant women, regardless of location or travel history, should be tested for Zika infection at every appointment.

This was a first for the continental United States; all of our previous cases have been in patients who travelled to a country with active transmission or by sexual contact with someone who had.

It represents a strong, if subtle pivot, from the previous message — non travel-associated Zika infection  was expected to be rare in the United States. Frieden frequently described his expectation that there would be small, local outbreaks of Zika that feature mosquito transmission, but they would be stamped out quickly.

We have known for some time that local transmission of Zika— which is associated with the devastating birth defect microcephaly, among other presentations— was possible and even probable in the Southeastern U.S. because of the presence of the yellow fever mosquito.

The advisory contains guidelines that are largely consistent with their message on Zika thus far: Pregnant women should not travel there. Men with pregnant partners should avoid the area or use barrier protection during sex; pregnant women and their male partners who are local should utilize insect repellant. They also recommended that women and their male partners avoid the area or postpone conception after visiting.

However, Frieden also said this morning that the yellow fever mosquito is a very difficult mosquito to control in urban environments. This is quite a correct assessment, but it seems rather inconsistent with the idea that the United States could expect small outbreaks that could be quickly controlled.

That is why the standard screening of pregnant women is a pivot, in my view. It seems to be overly vigilant if one expects only a small number of transmissions by a single vector. This recommendation is, to me, a tacit admission that we are dealing with some unknowns and it would be best to play things cautiously.

The CDC advisory describes factors of Zika prevention and guidelines for Zika infection monitoring. The missing piece of the story arc, of course, will have to be completed in the coming months. What are the recommendations for those pregnant women who test positive for Zika?

At this time, this is a tremendously open question. We do not yet know of any therapies. We do not yet know how to predict which pregnancies will result in stillbirths, microcephalic babies, or perfectly healthy babies. We don’t even know for certain the likelihood of any of those outcomes.

Prenatal examinations to detect microcephaly are not immediately possible for women diagnosed early in pregnancy, and these women have to wait several agonizing weeks to confirm or exclude it.

This infection is new to patients, but it’s also new to doctors. As frustrating as it is not to have solid answers to questions about the health of pregnancies, or to have to discuss guidelines that leave something of a cliffhanger, that is the situation we find ourselves in.

This does not mean that those issuing the guidelines don’t know what is going on, or that they are being flippant. It means that we are learning more and more, and implementing changes with each new finding. That is the best thing that can be done when the situation changes day to day.   

Zika is new to all of us, and the rules and guidelines are going to change fast and often.

Meghan A. May, M.S., Ph.D. is an Associate Professor of Microbiology and Infectious Diseases at the University of New England College of Osteopathic Medicine and on the American Society for Microbiology.


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