Deep Dive

What You Really Need to Know About Zika

Odds are, if you’re trying to conceive, you’ve been hearing about Zika. It’s left a lot of us wondering where it’s safe to travel, and what we’re supposed to do if we live in an area that might be at risk.

After going through all of the CDC’s publications on the subject, and speaking with the top seven CDC employees working on the Zika response, we’ve distilled this guide so that you know what the current Zika recommendations are (and we’ll periodically update it).

There’s a lot of nuance and complexity, which we cover below, but here are some quick things to know:

  • The reason Zika matters is mainly the high risk that if a mother is infected during pregnancy, her fetus, and eventual baby, will have severe health issues

  • The current recommendation: if you’ve traveled to an area with active Zika, don’t try to conceive for 8 weeks after as a female traveler, or 6 months as a male traveler.

  • Zika can still be passed as an STD from a man to a woman for 6 months. That means if you’re part of a heterosexual couple and you both traveled to an area with active Zika, don’t try to conceive for 6 months. (It seems the focus is usually on where women should travel, but the reality is where men travel has much more lasting implications for couples trying to conceive)

  • Testing isn’t easy or completely accurate. If you’re hoping to travel, then just get a test to make sure you didn’t get Zika before trying to conceive, this isn’t a great idea. A negative Zika test, unfortunately, doesn’t mean you didn’t get Zika.

  • Testing isn’t recommended for couples trying to conceive if neither partner has Zika symptoms (largely because of the accuracy issues above)

  • Areas with travel warnings include just about all of Central America and South America, the Caribbean, and the Pacific Islands. In Asia, the only official warning is in Singapore, but the CDC also recommends precautions for Southeast Asia (Thailand, Vietnam, and more). In the continental US, the only active Zika zones have been in South Florida (map of affected area here here) and coastal Texas (map of affected area here). Updated international maps can be found here.

The World of Zika: Unknowns and Best Guesses


You’ll notice as you read this that many of the suggested precautions are based on best guesses given the evidence that’s currently available. The Zika outbreak is still incredibly new, so what we know about the disease, its transmission, and its impacts are still not concrete. But, we do have some evidence from the current outbreak and lessons we’ve learned from other viral outbreaks which inform the current thinking and recommendations.

Zika & Trying to Conceive: Things to Know


Given the high risk of Zika infection early in pregnancy, there are special considerations for those trying to conceive. Most importantly, those trying to conceive must understand if they, their partner, their donor, or their gestational carrier have potentially been exposed to Zika, how long that risk continues, and what testing should or shouldn’t be done.

Be Zika-Free For Six Months (As A Couple) Before Trying To Conceive


At this time, the longest period Zika has been detected in women who aren’t pregnant is 8 weeks and in men it’s 6 months.

These numbers become crucial, especially in light of Zika’s potential to be sexually transmitted. Currently the CDC recommends that women wait at least 8 weeks to try to conceive following the start of Zika symptoms or their last possible exposure to the virus. The recommendation for men is to wait 6 months.

Most people focus on the woman, but the fact that Zika has been found in semen for as long as 188 days after symptoms appeared makes this more complicated. If a male-female couple has both traveled to an area with high Zika risk, they really need to take at least 6 months off from trying to conceive naturally, because the male partner could pass the virus on as an STD. Most couples who want to conceive wouldn’t be thrilled to use condoms for 6 months, which is why unnecessary travel to Zika areas should be avoided for many months in advance of wanting to try.

There’s No Test That Can Give You a Green Light Earlier


Testing isn’t recommended for couples who are trying to conceive, unless they have Zika symptoms. The reason is the lack of evidence to suggest the tests are accurate for people without symptoms. Testing might not diagnose Zika even if Zika is actually there—for example, a test might not detect Zika in the bloodstream even if Zika could be found in the semen. It’s possible testing would only give false reassurance. There’s a more in-depth explanation of testing below.

Assisted Reproductive Technology & Zika


So far, there haven’t been reports of Zika transmission through assisted reproductive technology (ART), but that doesn’t mean there aren’t risks.

A clear risk is presented if a couple has traveled to a Zika area and tries to conceive within 6 months using treatment like IUI -- we know Zika can be present in semen, so it’s possible that a woman could be infected during an IUI procedure. Most fertility clinics won’t start start treatment for any patients who have been exposed to Zika within 8 weeks for women and 6 months for men.

What is not yet known is whether individual gametes (sperm and eggs) can carry the virus. So it’s unclear whether isolating a single sperm using IVF with ICSI presents risk to either the resulting embryo or the mother. Likewise, if a woman froze her eggs last year following a trip to Brazil, are they now unsafe to use? Could the resulting embryo carry the virus? According to the CDC employees we spoke with, “the oocyte is just a big black box.” Meaning we have no idea. Theoretically it would be less likely, though, for a woman to be infected from her own oocytes because there’s evidence to suggest that once someone has gotten Zika virus they build an immunity to protect them from future Zika infection.

Currently, the CDC doesn’t have any special guidelines around storing frozen embryos, but some individual labs and cryobanks do, so you’ll want to check with them if you’re attempting a cycle during the timeframe where your embryos could possibly be affected.

For example, we spoke with April Batcheller, a reproductive endocrinologist at CCRM Minneapolis. Her clinic won’t perform a cycle if a patient has been to a Zika zone within 8 weeks. They recommend a 6 month waiting period, but if someone falls short of that, after signing informed consents, the clinic sends the embryos offsite for storage using a company called Reprotech, which uses vapor tanks for potentially affected embryos. They recommend not transferring the embryos for 6 more months. It’s these extra logistics, along with the added risks, that leads Dr. Batcheller to strongly urge her patients to avoid any travel that isn’t absolutely necessary to areas with Zika.

One way ART can help couples who want to conceive but are nervous about Zika -- if a male partner cannot avoid travel to active Zika areas, he can freeze sperm before his travels. Then, the couple can still attempt conception in the next few months using IUI or IVF (while using condoms to prevent potential infection of the female partner).

Donor Eggs & Donor Sperm


The good news is we can probably get a good sense of whether we’ve been exposed to Zika. That gets trickier when there’s a third party involved who you may not know.

The FDA has provided guidance to cryobanks on how to handle screening egg and sperm donors for Zika on a go-forward basis, but it’s not legally binding. It also doesn’t retroactively screen out donors who might have been exposed and had contaminated gametes before precautions were put in place.

The guidelines say that a donor is ineligible if they (1) have had a diagnosis of Zika in the past 6 months; (2) have lived in or traveled to an area with active Zika transmission in the past 6 months; or (3) have had sex in the past 6 months with a man who had Zika risk factors. When using known, rather than anonymous donors, as long as all parties are aware of any increased risk factors, sperm and eggs can be used.

The trickiest area is gaining confidence in purchasing frozen eggs or sperm from a bank, particularly if the samples were donated before the FDA guidance was issued, or before the risks of Zika were known. If you’re hoping to use a donor from a bank, one option would be to request only profiles of people who have donated in the months since guidelines have been followed, but that will limit candidates from what is likely already a small pool of donors who meet your criteria. Also, while donor agencies and banks can ask donors whether they’ve traveled to Zika areas, there’s no way for them to verify donors’ statements.

A Deeper Dive: The Details on Zika


The Primary Risk: Children Born With Congenital Zika Syndrome


The reason for the intense fear around Zika is the severity of downstream risks. The biggest risk posed by Zika is that the virus, when contracted by a pregnant woman, can be transmitted to her fetus, and the resulting child can develop devastating abnormalities as a result.

The most common birth defects that result are now referred to as “Congenital Zika Syndrome” and, in addition to cognitive, sensory, and motor disabilities shared with other birth defects, has hallmark characteristics of:

  • Severe microcephaly (small head size) resulting in a partially collapsed skull 

  • Decreased brain tissue with brain damage (as indicated by a specific pattern of calcium deposits)

  • Damage to the back of the eye with a specific pattern of scarring and increased pigment  

  • Limited range of joint motion, such as clubfoot  

  • Too much muscle tone restricting body movement soon after birth

Another risk that is, more rarely, associated with Zika is Guillain-Barre Syndrome (GBS). Current research suggests that GBS is strongly associated with Zika, even though only a small percentage of those affected with Zika develop GBS. GBS is an illness of the nervous system -- the immune system damages the nerve cells causing muscle weakness and even paralysis. Most people fully recover from GBS within several months, though some have permanent damage.

Likelihood Babies Will Develop CZS Following A Zika Pregnancy


The exact likelihood that a baby will develop CZS if a mother gets Zika is unknown, but there are some early estimates. The data from Brazil showed up to 13% of pregnancies where mothers contracted Zika in the first trimester resulted in infants with microcephaly. It looks like the first and early second trimester are the times of greatest risk, but there is some evidence to suggest that the third trimester can also lead to adverse outcomes.

One preliminary report from the US Zika Pregnancy Registry followed 442 women who had contracted Zika at some point during their pregnancies. Data showed about 6% of fetuses or infants from these mothers were affected by birth defects (21 infants born with birth defects from 395 live births, and 5 fetuses with birth defects from 47 pregnancy losses). Amongst the pregnant women who had Zika symptoms or exposure during the first trimester, the number of infant defects rose to 11%.

Importantly, the proportion of pregnancies affected by birth defects was the same whether or not the mother had symptoms.

Ways That People Contract Zika


There are a handful of ways someone can contract the Zika virus. The first, most obvious, means is by getting bitten by a mosquito with the virus.

But that’s far from the only way. Zika can also be passed on as a sexually transmitted disease, which raises a host of issue for couples trying to conceive that we mentioned above. There’s no evidence that the virus can be passed through saliva, but Zika has been found in semen for up to 188 days after the onset of infection.

Zika virus can be passed from a pregnant woman to her fetus during pregnancy or around the time of birth.

Passing of bodily fluids pose a risk for Zika transmission -- one example is through blood transfusions. Zika virus has been detected in breast milk, but there is not yet evidence that the virus can be transmitted through breastfeeding (so moms are still encouraged by the CDC to breastfeed).

It’s also possible that regular contact with blood or bodily fluids could lead to infection. One case of Zika was confirmed in Utah to someone with no known risk factors, but that person had cared for someone who did have the virus, so it’s possible it was contracted this way.

A current unknown is whether gametes (sperm or eggs) on their own can carry or transmit the virus.

Zika Symptoms


One of the things that makes Zika management so difficult is that, if you do contract Zika, there’s a good chance (up to 80%) that you won’t have any symptoms at all.

When symptoms are present, they’re usually mild and last for a few days to a week. The most common symptoms are fever, rash, joint pain, and conjunctivitis (red eyes). Others include muscle pain and headache.

Because most of these symptoms could also just result from a common cold, it’s hypothesized that many cases of Zika go undetected.

The Current State Of Zika In The US


In the US to date, there have been over 5,000 cases of Zika. Most people were infected traveling outside the US, but over 200 cases are presumed to have been acquired by mosquitos locally in the US, with over 200 from Florida and 6 from Texas. Currently over 70 cases are attributed to other methods of infection, with at least 40 being linked to sexual transmission and 20 from congenital infection.

Looking at the US territories (which includes Puerto Rico), the numbers are far higher, with over 37,000 reported cases that are almost all attributed to local mosquito transmission.

As of today, there have been over 1,400 pregnant women in the US, and over 3,000 pregnant women in the US territories, who have tested positive for Zika. But the CDC estimates that in 2016 more than 10,000 pregnant women may be infected in Puerto Rico alone.

Where in the World is… Zika?


In the US, there have been a handful of geographies affected by local Zika mosquito transmission -- south Florida (maps here) and Brownsville Texas (map here). These are areas that pregnant women or those planning to conceive should avoid traveling to.

Zika in US territories has been extensively documented in Puerto Rico, and there have also been confirmed transmissions in the US Virgin Islands and American Samoa.

As far as destinations internationally that should be avoided for pregnant women or couples trying to conceive, the list is (very) long. You can always check the updates and exact locations here, but generally speaking travel advisories are in place for all of Central America, the Caribbean, and South America. The Pacific Islands are also on that list, for example Fiji and Papua New Guinea.

Currently the only active travel notice in Asia is for Singapore, but there are special considerations in place for much of Southeast Asia, where the CDC says the risk isn’t high enough to warrant a full travel notice, but there are local transmissions so pregnant women (or couples trying to conceive) should consult with a physician before travel to places like Thailand, Vietnam, Cambodia, or countries near that geography (full list here).

Testing For Zika


Unfortunately, like so much on the subject of Zika, testing isn’t clear cut – diagnosing Zika isn’t just a standard lab test like checking a Vitamin D level. There are a few types of tests to know about, and a long list of reasons you won’t want to put too much faith in the results of any at this point.

At a very high level there are two types of tests. The first kind of test, RNA nucleic acid testing (NAT), screens both blood and urine for active Zika virus. This needs to be conducted within the first two weeks after symptoms appear or after exposure if the patient is asymptomatic.

If the RNA NAT test is positive, it’s definitive -- there really is Zika virus present. If it’s negative, though, it doesn’t mean that someone is Zika free.

If the RNA NAT comes back negative, a second type of testing will be performed, which looks for immune signals that the body has built up antibodies to Zika, giving hints that the virus was there. These antibodies typically develop toward the end of the first week of a virus and can be tested for between 2 - 12 weeks after exposure.

But, these antibody tests aren’t black and white -- a positive IgM antibody test doesn’t always really mean that someone had Zika. It could mean that someone had another flavivirus (like dengue fever), or even just that someone had a previous vaccination against a flavivirus (like yellow fever). And negative tests also don’t definitively mean someone is in the clear, as antibodies decline over time, especially 12 weeks or more after exposure.

Unfortunately, there are no available tests that show how likely someone is to pass Zika on through sex. Even though we know that Zika can be present in semen when none is found in blood, there are currently no approved tests for semen.

You might be wondering why this has to be so complicated. First off, the tests are still being developed. Zika wasn’t something anybody was worried about until the very recent outbreak started in Brazil, and tests are evolving in an attempt to keep up. There aren’t a lot of facilities that can run the current tests, which is why samples are currently shipped to the CDC or a state health department.

More details on testing can be found here.

If You’re Pregnant And Might Have Been Exposed


If you’re pregnant and you live in, or have traveled to, an area with active Zika, it’s recommended that you get tested as soon as possible. If it’s beyond the two week period when the RNA NAT test can show the virus, then IgM antibody testing should take place, and should continue to be done periodically at prenatal visits.

If all tests are negative, your doctor will still consider doing serial fetal ultrasounds. But it’s unclear how useful this really is in detecting CZS in utero, and an article published in the journal Ultrasound in Obstetrics and Gynecology places the odds of successfully diagnosing with ultrasound at slightly better than a coin flip. Also, while there is the option to do an amniocentesis to test for Zika, but it’s unclear if this method actually works.

Precautions If You Can’t Avoid Travel Or Live In An Area With Active Zika Transmission


Whether you’re pregnant or trying to conceive, the best thing you can do to avoid contracting Zika virus (if you live in an at-risk area) is to avoid mosquito bites and avoid sexual contact with anyone who might be at risk.

For mosquito prevention, it’s recommended that you stay indoors as much as possible, in places with air conditioning and screen doors. Avoid areas with standing water. Wear long-sleeved shirts and long pants. Treat your clothing and gear with permethrin, or buy pre-treated clothing (except for in Puerto Rico, where permethrin isn’t effective).

If you do have exposed skin, use EPA registered insect repellents with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol, or 2-undecanone. This is true even if pregnant or breastfeeding, as the risk of Zika outweighs the risks from the chemicals in insect repellent.

If you have small children there’s more information here about protecting them from mosquitos, and if you live in an area with active Zika there is detailed information here about more steps you can take in your home to eradicate mosquitos.

As far as sexual transmission, condoms should be used for sex with female partners up to 8 weeks after exposure, and with male partners up to 6 months after exposure.

Last Updated February 24, 2017

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