Zika Virus: Everything Pregnant Women Should Know

January 23, 2020

Zika Virus: Everything Pregnant Women Should Know

This mosquito-borne illness can threaten your unborn baby's health. Here's what you need to know about the Zika virus.

If you're pregnant—or trying to conceive—the Zika virus is probably a top-of-mind concern right now, and with good reason: This mosquito-borne virus is dominating headlines with its scary multi-country advance and potentially devastating consequences for pregnant women and their babies.

Zika surfaced just over a year ago in South America, and Brazil has been disproportionately affected, with thousands of babies suffering severe birth defects, including brain damage, in utero when their mothers contracted the virus. But it has now spread to more than three dozen countries and territories in the Americas, and has recently landed in the United States (although it's important to note that these U.S. cases were brought by returning travelers from affected regions). According to the Centers for Disease Control and Prevention (CDC), 168 pregnant women in the US and the District of Columbia have been diagnosed with Zika and another 142 have been identified in the US territories, which includes the US Virgin Islands and Puerto Rico.

Per the CDC, mosquitoes in the continental United States or Hawaii have not spread Zika. However, lab tests have confirmed Zika virus in travelers returning to the United States. These travelers have gotten the virus from mosquito bites and some non-travelers got Zika through sex with a traveler. Cases of local transmission have been confirmed in three US territories: Puerto Rico, the US Virgin Islands, and American Samoa.

The virus is likely to spread further, according to the World Health Organization (WHO), because the mosquito that transmits Zika is in all but two countries of the Americas, and the people in these regions lack immunity to the virus.

If you're expecting (and frankly, even if you're not), it's crucial to arm yourself with information and up-to-date advice. This is what you need to know:

What is Zika virus?

The Zika virus is an insect-borne illness that can be primarily transmitted by infected Aedes mosquitoes, the same kind that carry dengue and yellow fever. The name comes from the Zika Forest in Uganda where monkeys with the virus were first found in 1947.

Why is it dangerous?

For the relatively few people who show signs of a Zika infection, the illness is often very mild. But in pregnant woman, the effects can be devastating, and can include pregnancy loss or a baby born with an abnormally small head and brain—a condition known as microcephaly, says Edward R.B. McCabe, M.D., Ph.D., Senior Vice President and Chief Medical Officer of the March of Dimes. Microcephaly may be associated with developmental delays, mental retardation, and seizures, and in some cases can be fatal.

Until recently, Zika virus had only been associated with significant risk to the fetus—it wasn’t established that the effects were actually caused by it. But now the news has changed and health officials can report a direct link between Zika and microcephaly. Still, there are many unknowns—including how likely it is that an infection in a pregnant woman will be passed on to her fetus; whether some fetuses are infected but don't develop microcephaly; how often pregnancy loss may occur in expecting women with Zika virus; and whether pregnancy makes women more susceptible to the virus, says MarjorieTreadwell, M.D., director of the Fetal Diagnostic Center at the University of Michigan and a maternal and fetal medicine expert.

To date, there have been no infants born with microcephaly and other poor outcomes linked to locally acquired Zika virus infection during pregnancy in the continental United States. One infant with microcephaly linked to travel-associated Zika virus infection during pregnancy has been reported in Hawaii as well as one with microcephaly born in a hospital in New Jersey to a woman who had previously tested positive for Zika virus infection and had traveled to Central America during pregnancy.

While the Zika virus remains in the blood of an infected person for a few days to a week, according to the CDC, there's no current evidence to suggest that it poses a risk of birth defects in future pregnancies. And Zika won't cause infections in a baby that's conceived after the virus has left the bloodstream.

How is Zika transmitted?

Zika is primarily spread through the bite of infected mosquitos. When a mosquito bites and draws blood from someone who's infected, the insect itself becomes infected and then goes on to bite other people.

The CDC continues to investigate and track cases of Zika virus infection, including a few pregnant women, that have been transmitted sexually (there are 11 so far, as of late May). This type of transfer is surprising—and of great concern—because it could indicate that sexual transmission may be easier and more likely than experts once believed. In each of the confirmed cases so far, a man who had traveled to a region affected by Zika then passed the virus to his female partner (it's not yet known if women can pass Zika to men).

The Zika virus can also be transmitted from mother to baby during pregnancy or around the time of birth, but according to the American College of Obstetricians and Gynecologists (ACOG), there are no clinical studies to measure the risk to an unborn child if the mother is infected. In rare instances, the Zika virus may be passed along via a blood transfusion, according to the CDC.

Zika virus has been detected in fetal tissue, amniotic fluid, full-term infants, and in the placenta, according to ACOG, and trace amounts of the virus have also been found in breast milk, but because the amount is tiny, it's unlikely to pose a threat. Oral infections of Zika haven't been documented and, if one were to occur, it would likely be the same mild version as seen in adults. The many benefits of breastfeeding outweigh this possible risk.

What are the symptoms of Zika?

A Zika infection is similar to a mild case of the flu and may include such symptoms as a low-grade fever, headache, rash, muscle and joint pain, and conjunctivitis (pink eye). Symptoms may last several days to a week. Only 20 percent of people infected with the Zika virus will actually become ill, reports Cynthia Moore, M.D., Ph.D., of the National Center on Birth Defects and Developmental Disabilities at the Centers for Disease Control and Prevention (CDC), adding, "We don't know at this time if pregnant women are more likely to develop symptoms if infected."

Testing for Zika virus

According to the CDC, the FDA still hasn’t approved a commercially available diagnostic test for Zika virus. But two institutions in Texas did develop the first rapid hospital-based ones. Scientists at Texas Children's Hospital and Houston Methodist Hospital can directly detect Zika's genetic material or ribonucleic acid (RNA) in a pregnant woman's amniotic fluid, or anytime in blood, urine, amniotic or spinal fluid and provide results in a matter of hours. This test is currently available to hospital patients who've traveled to an affected region and are experiencing acute symptoms of Zika.

Several state and territory health departments are also able to test for Zika, but the test isn't perfect. "Because it cross reacts with other related viruses, it's possible to have a positive test but not actually have the Zika virus," says Treadwell. Because of this, the CDC had previously advised the test only for people who'd been exposed (i.e., traveled to a high-risk country) and showed symptoms.

Now, the guidelines urge asymptomatic pregnant women who've been to places with known ongoing Zika transmission be tested between 2 and 12 weeks after they've returned—or right away if symptoms are present. The CDC also recommends that pregnant women without symptoms but who live in a Zika-affected area be tested for the virus at the start of prenatal care as well as later on, at the mid point of the second trimester. Even if you don't show signs, your unborn baby should be examined, usually via ultrasound. If there are concerns following an ultrasound, amniocentesis may be the next step.

Federal health officials are urging that newborns be tested if the mother has visited an affected area and also exhibits symptoms of the Zika virus. Your doctor should contact a health department for information about testing for Zika. Even if you don't show signs, your unborn baby should be examined, usually via ultrasound. If there are concerns following an ultrasound, amniocentesis may be the next step.

Underscoring the gravity of Zika and its potential spread to the United States, President Obama requested approximately $1.9 billion in emergency funding from Congress in February—money that will be earmarked for research to create vaccines and diagnostic tests for Zika and to aid U.S. territories, including Puerto Rico and the Virgin Islands, where cases of the virus have been confirmed. This money will also go toward mosquito-control programs in at-risk southern U.S. states.

Reducing the risk

New guidance from the CDC now directs pregnant women to be very cautious when it comes to having sex with a partner who's traveled to a region affected by Zika. Couples should use condoms during all forms of sex to reduce the risk of potential transmission or abstain entirely for the duration of the pregnancy. It's unknown how long men should use condoms during sex because the viability of Zika in sperm still isn't clear.

Because there's no vaccine for Zika, you can further reduce your risk by staying current with the latest recommendations. If you're pregnant, delay travel to the regions listed in the CDC's advisory (see below). If travel can't be avoided, take every precaution to avoid mosquito bites, including:

  • Wearing shirts with long sleeves and pants, rather than shorts
  • Using bug spray with DEET, which is safe for pregnant and nursing women (check the label and follow the directions carefully
  • Treating clothes with permethrin, a type of insecticide

If you aren't pregnant but have concerns because your male partner has been to a Zika-affected region, you can use condoms or abstain, notes the CDC. However, simply visiting the region isn't the only factor for contracting the disease. Risk also depends on a person's length of stay, how many mosquito bites he received and whether prevention measures were taken to prevent the bites.

For those couples who want to have a baby with a male partner who's recently traveled or lived in an exposed area, ask your doctor for advice. A Zika test may be possible but priority will first be given to women who are already pregnant. 

The latest recommendations

The CDC has issued a level-2 travel notice urging women who are pregnant to avoid visiting the following countries: American Samoa, Barbados, Bolivia, Brazil, Cape Verde, Colombia, Commonwealth of Puerto Rico—US Territory, Costa Rica, Curacao, Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Mexico, Nicaragua, Panama, Paraguay, Saint Martin, Samoa, Suriname, Tonga, U.S. Virgin Islands, and Venezuela.

This list is changing almost daily, so it's important to check the CDC's travel information site for updates.

Pregnant women in any trimester—as well as women who are trying to become pregnant or thinking about becoming pregnant—should talk to their doctor or other healthcare provider before traveling to these areas and strictly follow steps to avoid mosquito bites during the trip.

Reference: Parents