The best advice on Zika virus and pregnancy is to know the unknowns

Everything about the Zika virus is scary. The fact that Zika covertly infects most people with nary a fever is frightening. What the virus seems capable of doing to fetuses is profoundly inhumane and terrifying. But scariest of all — for me, anyway — is the unknown.

It is deeply unsettling to be faced with such a mysterious and seemingly dangerous threat. The science, as they say, is evolving, and because of that flux, public health officials have been scrambling to give advice, particularly for pregnant women or women who want to become pregnant, on firm footing.

The reason for the alarm began in Brazil with an ominous spike in cases of a rare birth defect called microcephaly, a disorder marked by unusually small heads and abnormal brain development. Genetics, severe malnutrition and excessive alcohol can cause microcephaly, as can certain infections such as rubella. But this Brazilian uptick coincided with a rise in Zika infections, leaving scientists alarmed that the virus might be to blame.

The link remains unproven, but the evidence is pointing that way. Scientists recently found the entire Zika virus genome in neural tissue from a fetus with a severely damaged brain. Those results, described February 10 in the New England Journal of Medicine, and others suggest that the virus is indeed causing trouble in some fetal brains.

Pay attention to that “some.” No one knows how often the virus moves from mother to fetus. “Is it one in 1,000 pregnant women? One in 100? Or one in 10?” asks infectious disease specialist William Schaffner of Vanderbilt University Medical Center in Nashville. “We don’t know the magnitude of the risk, and that makes everybody uneasy.”

Another big unknown has to do with the 80 percent of people who get a Zika infection but don’t show symptoms, Schaffner says. It’s possible that people who feel Zika’s fever, pain and red eyes have higher virus loads in their bloodstream and have a greater chance of passing that virus along. Scientists just haven’t been able to test that.

It’s also unclear just how the virus moves from person to person. Mosquitoes clearly carry Zika, but so can sperm, three recent case studies suggest. And how long the virus can live in sperm isn’t known. To confound matters, Zika may lurk in saliva, urine and breastmilk, but scientists don’t know if those fluids can transmit the infection.

All of this uncertainty leaves some groups of people particularly unsettled: “This is a scary time for women who are thinking about having a baby and who are pregnant,” says Wendy Sue Swanson, a pediatrician and executive director of digital health at Seattle Children’s Hospital. “We’re taking an already nervous group and we’re making them more nervous.”

So what should these women do? If you live in the United States, haven’t traveled to a place where Zika is circulating, and want to have a baby, go right ahead, Swanson says. “Women who are living in the United States and not traveling are very safe.”

If you are traveling to a place with Zika and want to get pregnant soon, it might be worthwhile to wait a few weeks after you’re back before trying to get pregnant. The virus seems to clear out of women’s bodies by a week after infection, Schaffner says.  

It’s another story for men, though. Zika may hide for longer in semen, which is why the Centers for Disease Control and Prevention has now recommended that men who have traveled to Zika-affected areas use condoms indefinitely if they are concerned about transmitting the virus. “They [the CDC] avoid the question of how long,” Schaffner says. “They don’t know yet.”

Of course, indefinite condom use puts a real damper on procreative activities. CDC recommends that couples trying for a pregnancy talk with their health care provider and consider getting testing for the virus.

If you’re already pregnant, talk to your health care provider and consider changing travel plans if you’re going to a place where Zika-carrying mosquitoes are biting, Swanson says. And if you live in places like South Florida where the type of mosquito that carries Zika lives, be mindful of avoiding bites.

Circumstances in the United States make it unlikely that Zika will get a toehold and spread. “Zika is not going to become widespread here,” Schaffner says. We spend a lot of time indoors, our windows have screens, and we use air conditioners, he says, all factors that can reduce exposure to mosquito bites. What’s more, we have a strong public health system that can monitor the virus and respond with mosquito abatement efforts. Other viruses such as dengue and chikungunya haven’t established themselves in the United States, Schaffner points out. Zika may behave similarly.

Swanson recommends approaching a potential Zika infection during pregnancy as you would any other aspect of health. “What we have to do is think carefully about how to make sure we decrease any risks, and that goes along with all the other things we do when we’re preparing for having a baby,” she says. “Keeping our bodies healthy, eating the right foods, staying away from toxins in the environment, taking prenatal vitamins, exercising” — those are behaviors that can point a woman and baby toward better outcomes. In the same way, thinking hard about travel, possibly timing a pregnancy around travel plans and using mosquito repellent could perhaps cut the already small risk of Zika infection.

So while the unknowns about Zika virus are alarming, I’m not feeling afraid. My predominant reaction has been one of sorrow for the people affected, and gratitude that I have the dumb luck to live in a place where this virus isn’t spreading.