How to Prevent the Zika Virus

While the Zika virus usually only causes mild, self-limiting illness, the transmission of the virus during pregnancy can be serious and lead to a rare birth defect known as microcephaly. Because there is neither a vaccine nor treatment for the Zika virus, the only way to prevent infection is to avoid mosquito bites if traveling to or living in an area where the Zika risk is high.

Moreover, if you are pregnant, you would need to either use condoms every time you have sex or abstain from sex until your doctor tells you otherwise.

Preventing Mosquito Bites

The Zika virus is primarily spread by the Aedes aegypti mosquito, a strain prevalent in tropical and subtropical regions throughout the planet. Unlike other mosquitoes, the Aedes aegypti is most active during the day. The mosquito can be recognized by white markings on its legs and a marking on its back in the shape of a lyre.

Most Zika outbreaks will occur during the spring and summer months when the mosquito is actively breeding. In the northern hemisphere, the season could start as early as April and end in November when temperatures drop below 50 degrees Fahrenheit. In the southern hemisphere, the opposite would be true, with the season running from September through May. The risk is highest during the height of summer.

The Aedes aegypti mosquito can be found in most equatorial countries but is associated with large-scale infestations in South America, Central America, and the Caribbean, Central and East Africa, India, Southeast Asia, and northern Australia. In the U.S., the mosquito is most commonly seen on the Gulf Coast running from Texas to Florida.

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.
• Wear protective clothing. This includes wearing long sleeves, long pants, socks, and shoes. Pant legs can be tucked into 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 even small amounts of water 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 travel advisories. If the Zika risk is high, either change your plans or postpone your trip to cooler autumn or winter months.

Preventing Sexual Exposure

Avoiding Zika during pregnancy requires a two-prong approach: preventing mosquito bites and avoiding exposure during oral, vaginal, or anal sex.

If you are pregnant, it is best to avoid traveling to countries where the virus is endemic. If your partner has just returned from such an area, there are several things you both can do to protect yourself:

• Use condoms. The CDC currently recommends using condoms for at least eight weeks following the return of your partner if asymptomatic (without symptoms) and at least six months if he is symptomatic. Short of abstinence, this is the best all-around form of protection.
• Use insect repellent. This should be used by both you and your partner for at least three weeks following his return. Doing so may prevent human-mosquito-human transmission.

• Use dental dams during oral sex. (You can even make one if needed.)
• Avoid sharing sex toys. Alternately, you can use condoms on sex toys and disinfect the toy between uses.

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

If you have been trying to conceive, you may want to delay your plans until a doctor or infectious disease specialist tells you otherwise. Research has shown that the Zika virus can persist in semen for as long as 188 days following symptoms. During this time, if the virus is passed to the mother, it can lead to a potentially devastating birth defect known as microcephaly in which the baby is born with an abnormally small head and brain.

Preventing Blood Exposure

While there have been several cases in Brazil where the Zika virus has been passed through a blood transfusion, the risk is considered low. While research is ongoing, current evidence suggests that the virus is less able to persist in blood and will likely clear within 13 days.

Newly implemented guidelines by the U.S. Food and Drug Administration further reduces the risk by routinely screening blood donations and removing any which tests positive for the Zika virus from the blood supply.

If this doesn't offer you enough assurance, you can make an autologous donation by which you donate blood for yourself prior to a surgery or planned medical procedure. Autologous donations require a doctor's prescription. Contact your provider to find out if you are eligible to make such a donation.

Vaccine Development

In March 2017, a Phase II human trial was approved to test a genetically engineered vaccine based on the same model used to develop a West Nile virus vaccine. A total of 80 participants were registered for the trial which will be conducted over three years at three sites in the United States.

The investigational vaccine contains genes that, when injected into the arm, provides the body with the information needed to build Zika-like particles. While these particles are not infectious, the immune system will respond to them as if they were and launch an immune defense. The same model has been used successfully in creating vaccines for other viral diseases.

Should the results of the two-stage trial be successful, Phase III testing may begin by as early as 2020. Other vaccine models are in the preliminary stages of investigation.

Sources:

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.

Paz-Bailey G, Rosenberg E, Doyle K, et al. "Persistence of Zika Virus in Body Fluids — Preliminary Report." N Eng J M. 2017. DOI: 10.1056/NEJMoa1613108.