Is Zika a Sexually Transmitted Disease?

Close-Up Of Zika Vaccine, Birth Control Pills And Condom On Black Background
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Zika is a mosquito-borne virus that has been  of growing concern in many areas of Central and South America as well as the southern United States. During the spring and summer of 2016, Zika caused a major public health emergency. Although initial symptoms of Zika are relatively minor, the virus can cause serious problems in pregnant women and their developing babies. Infection with Zika during pregnancy can lead to problems including:

  • Microcephaly. This is a condition where a baby has an abnormally small head. It can lead to numerous problems that range from mild to severe. 
  • Fetal brain damage
  • Eye problems
  • Hearing problems
  • Growth problems

It is unclear how often Zika infection during pregnancy leads to these problems. The children of some pregnant women infected with Zika have no problems at all. Others are born with conditions that can lead to life-long disability.

What is the Evidence Zika Can Be Transmitted During Sex?

Zika can be sexually transmitted, but originally it was primarily thought of as a mosquito-borne illness. As Aedes mosquitoes require a specific climate, that was believed to limit transmission. However, as cases of sexually-transmitted Zika started showing across more than four continents, researchers realized that the spread of the virus is not limited by climate. It's also affected by behavior. 

Several studies have shown that Zika virus is present in semen and saliva.

Interestingly Zika seems to stay in the semen longer than in the blood. Therefore, a negative blood test does not necessarily mean that a previously infected person is entirely free of the virus.

In addition, there have also been cases of Zika reported where the only known exposure is through sexual or otherwise intimate contact.

It appears that sexual transmission can occur before symptoms appear as well as during symptomatic disease of after symptoms resolve. 

Concerns about sexual transmission of Zika are grave enough that the Centers for Disease Control have released guidelines on how to prevent it. Prevention is particularly important for pregnant women and women who are at risk of pregnancy. Although symptoms in non-pregnant adults are usually mild, infection during pregnancy can be devastating. 

At this point, doctors do not know if the risks associated with sexually-transmitted Zika are different than those associated with mosquito-borne illness. 

How Can You Reduce the Risk of Sexually Transmitted Zika?

According to the CDC, consistent and correct condom use can prevent the spread of Zika during sexual encounters. Men who live in, or have traveled to, areas where Zika is common and have pregnant partners should take the most in-depth precautions. They should either abstain from sex or use condoms throughout the course of the pregnancy.

This includes using condoms or other barriers for oral sex and anal sex as well as vaginal sex

Men whose partners are not pregnant should also be aware of the risk of transmitting Zika. If men live in or have traveled to a place where Zika is common, they should talk about it with their partner(s). They should also be aware that it is unclear how long someone who has been infected with Zika can transmit the virus sexually. Therefore, if there is a risk a partner could become pregnant, it may be wise to take precautions. Men may also want to be careful if they are having sex with another man and that man has a female partner who is or could become pregnant.

Sexual transmission of Zika is less of a concern for individuals who can not become pregnant. Although it can still occur, symptoms of Zika are usually mild in otherwise healthy adults. Therefore, although it makes sense to avoid infection if possible, it's not terrible if it occurs. 

Smart Management of Zika

News stories about Zika can be terrifying, particularly if you're pregnant. However, it's important to understand that Zika risk can be managed, if not eliminated. If you're pregnant or thinking of becoming pregnant, Zika should only be a concern if:

  • You live in a region where Zika is common
  • You have traveled, or are going to travel, to such an area
  • You have a sexual partner who has lived in or traveled to an area with Zika

Even if one of those things is true, there are things you can do to reduce your risk of infection. You can wear long sleeves and  long pants when in mosquito infected areas. You can sleep with mosquito netting and use appropriate bug sprays. You can also practice safe sex consistently and correctly. 

Note: Some countries where Zika is common have begun to urge women to postpone their pregnancies until Zika is under control. However, that is only something to be considered if you are living in such an area. If you don't, you might want to avoid travel to Zika areas while you're pregnant. When that's not possible, talk to your doctor about the precautions you can and should take. 

Sources:

D'Ortenzio E, Matheron S, Yazdanpanah Y, de Lamballerie X, Hubert B, Piorkowski G, Maquart M, Descamps D, Damond F, Leparc-Goffart I. Evidence of Sexual Transmission of Zika Virus. N Engl J Med. 2016 Jun 2;374(22):2195-8. doi:  10.1056/NEJMc1604449

Gao D, Lou Y, He D, Porco TC, Kuang Y, Chowell G, Ruan S. Prevention and Control of Zika as a Mosquito-Borne and Sexually Transmitted Disease: A Mathematical Modeling Analysis. Sci Rep. 2016 Jun 17;6:28070. doi: 10.1038/srep28070.

Oster AM, Brooks JT, Stryker JE, Kachur RE, Mead P, Pesik NT, Petersen LR. Interim Guidelines for Prevention of Sexual Transmission of Zika Virus - United States, 2016. MMWR Morb Mortal Wkly Rep. 2016 Feb 12;65(5):120-1. doi: 10.15585/mmwr.mm6505e1. 

Turmel JM, Abgueguen P, Hubert B, Vandamme YM, Maquart M, Le Guillou-Guillemette H, Leparc-Goffart I. Late sexual transmission of Zika virus related to persistence in the semen. Lancet. 2016 Jun 18;387(10037):2501. doi: 10.1016/S0140-6736(16)30775-9.

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