How to Prevent the Zika Virus

Avoiding Infection When Pregnant or Traveling

Zika virus research
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While we tend to think of the Zika virus as mosquito-borne illness, it can be transmitted from mother to child during pregnancy and even passed from person to person through unprotected sex.

The Zika virus was first identified in Uganda back in 1947. However, it was only 2015 that it made world headlines as a strain of the virus cut a path of infection from South and Central America right up into the southern part of the United States.


For most people, a Zika infection will have little, if any, effect. In fact, as many as 80 percent of infections will have no symptoms. Those that do will often appear flu-like with mild fever, body aches, headache, and possibly a rash. Less commonly, the infection can lead to a serious condition known as Guillain-Barré syndrome in which a person's immune system attacks its own nerve cells.

The greater concern involves the development of a Zika infection during pregnancy. In some cases, it can lead to miscarriage, and, in others, a potentially devastating birth defect known an microcephaly in which the child is born with an abnormally small head and brain.

While there is currently no treatment or cure for the Zika virus, there are several ways you can protect yourself.

Preventing Mosquito-Borne Infection

The Zika virus is primarily spread by the Aedes aegypti mosquito, a strain prevalent in tropical and subtropical regions across the planet.

Unlike other mosquitoes, the Aedes aegypti is most active during the day. Most Zika outbreaks will occur during the spring and summer months when the mosquito is actively breeding.

The mosquito itself can be identified by white markings on its legs and a marking on its back in the shape of a lyre.

The Aedes aegypti mosquito is distributed throughout most of South America, Central America, the Caribbean, Central and East Africa, India, Asia, and northern Australia, In the U.S., the mosquito is most commonly seen on the Gulf Coast.

If living in or traveling to these areas, there are certain things you can do to prevent mosquito bites:

  • Use an insect repellent. Options include those made with DEET (minimum 10 percent concentration), picaridin (also known as icaridin or KBR 3023), and oil of lemon eucalyptus (found in SkinSmart and Skin So Soft Bug Guard).
  • Wear protective clothing. This includes long sleeves, long pants, socks, and shoes. Pant legs can also be tucked into the boots or socks for added protection.
  • Sleep under a mosquito net. Repellent-infused netting is available through specialty retailers.
  • Get rid of standing water. Mosquitoes can breed in small amounts of water in and around the house. This includes flower vases and blocked gutters.
  • Keep mosquitoes from getting inside. Close windows and vents and use an air conditioner if it is especially hot.
  • Check health advisories before traveling. The Centers for Disease Control and Prevention (CDC) offers regularly updated Zika advisories. Avoid areas where Zika is endemic or postpone your trip to cooler autumn or winter months.

Pregnancy Risks

Avoiding Zika during pregnancy requires a two-prong approach: preventing exposure from mosquitoes and avoiding infection from sexual partners.

When formulating a strategy, it is important to understand that the risk of birth defects is greatest during the earliest stages of the first trimester. This is the period when fetal stem cells are only just beginning to specialize and develop into skin, bones, and organs (such as the heart, eyes, and brain). Infections during the second or third trimester rarely cause any damage.

It is during this vulnerable early stage of development that the Zika virus can reap the most harm. Microcephaly, the most serious complication, can occur in anywhere from one percent to 13 percent of affected pregnancies and lead to lifelong physical and intellectual disabilities.

Preventing Mother-to-Child Transmission

While the same tools for prevention can be used to prevent mosquito bites, extra care needs to be taken to avoid exposure during sex. This includes the avoidance of unprotected oral, vaginal, or anal sex.

Because the virus can be found in high concentrations in semen, the route of infection almost always goes from man to woman. (By contrast, the Zika virus is less able to thrive in saliva or vaginal secretions, making female-to-male transmission far less likely.)

If you are pregnant or plan to get pregnant, it is best to avoid traveling to places where the virus is endemic. If your partner has just returned from an endemic region, there are several ways to protect yourself:

  • Use condoms. The CDC currently recommends using condoms for at least eight weeks following the return if your partner is asymptomatic (without symptoms) and at least six months if your partner is symptomatic.
  • Use insect repellent. This should be used by both you and your partner for at least three weeks following the return. Doing so may prevent human-mosquito-human transmission.
  • Use dental dams for oral sex. (You can even make one if needed.)
  • Avoid sharing sex toys. Alternately, you can use a condom on sex toys and simply disinfect the toy between uses.

If your partner has or develops symptoms of Zika upon his return, testing should be sought from the municipal or state health department. Neither preconception testing nor the testing of an asymptomatic partner is currently recommended.

Blood Transfusion Risk

The risk that the Zika virus poses to the blood supply is unclear. While there have been a few credible cases in Brazil linked to platelet transfusions (typically used to treat hemophiliacs or persons undergoing chemotherapy), there have been no similar occurrences elsewhere.

On August 26, 2016, the U.S. Food and Drug Administration issued new guidelines on the screening of blood donations in the U.S. Today, any donation that tests positive for the Zika virus will be removed from the blood supply.

Vaccine Development

There is currently no vaccine to protect against the Zika virus.

As of March 2017, a Phase II human trial was approved to test a DNA vaccine based on the same structural components used to develop a West Nile virus vaccine. Should the result of the two-stage trial be successful, Phase III testing may begin by as early as 2020.

Other Zika vaccine models are in preliminary stages of investigation.


Epelboin, Y.; Talaga, S.; Epelboin, L. et al. "Zika virus: An updated review of competent or naturally infected mosquitoes." PLoS Negl Trop Dis. 2017; 11(11):e0005933. DOI: 10.1371/journal.pntd.0005933.

Centers for Disease Control and Prevention. "Clinical Guidance for Healthcare Providers for Prevention of Sexual Transmission of Zika Virus." Atlanta, Georgia; updated December 13, 2016.

Gao, D.; Lou, Y.; He, D. et al. "Prevention and Control of Zika as a Mosquito-Borne and Sexually Transmitted Disease: A Mathematical Modeling Analysis." Sci Rep. 2016;6:28070. DOI: 10.1038/srep28070.

National Institutes of Health. "NIH begins testing investigational Zika vaccine in humans." Bethesda, Maryland; issued August 3, 2016.