STD Awareness: Sexual Transmission of Zika Virus


Zika virus. Image: Cynthia Goldsmith, CDC

I first heard of Zika virus in an epidemiology class, when another student made on offhand remark: “Did you know Zika virus can be transmitted sexually?” Ever vigilant for material for the STD Awareness column, I excitedly scribbled the name of the virus in my notes. But upon further investigation, I found that there were only a couple of documented cases of the sexual transmission of this virus that no one had heard of, and decided there was no reason to freak people out about yet another potential STD when rates of more common STDs, like chlamydia and gonorrhea, were on the upswing.

A year later, Zika virus was splashed across headlines on a daily basis, mostly for its newfound association with birth defects, but also in light of revelations that it could be transmitted by sex.

Access to condoms and reliable contraception is more vital than ever.

While Zika virus is usually transmitted by mosquito bites, the discovery that it can be sexually transmitted made it the only known virus that could be spread both sexually and by mosquitoes. It’s also the only known mosquito-borne virus that can cross the placenta to harm a fetus. Like several other viruses, including CMV and rubella, Zika is implicated in serious birth defects. But many health authorities worry that its potential as a sexually transmitted pathogen is dangerously underestimated. As of August 31, there have been 23 confirmed sexually transmitted cases of Zika virus in the United States — but sexual transmission will rise as the virus jumps into local mosquitoes, which will also make it difficult or impossible to tell if a sexually active Zika patient got the virus from sex or directly from a mosquito.

Earlier this year, sexually transmitted Zika virus in Texas made headlines, with many journalists incorrectly proclaiming it the first known case of sexual transmission. In fact, Zika’s sexual transmission was first documented in 2008, before “Zika” was a household name and the married couple who published their experience in a scientific paper thought they could share their STD status in relative obscurity. Despite referring to themselves as “Patient 1” and “Patient 3,” a science reporter quickly figured it out and (with their permission) revealed their identities in a 2011 article — still years before Zika-bearing mosquitoes would hit the Americas and trigger a microcephaly epidemic that propelled the virus to infamy.

Eight years after that first known sexual transmission of Zika, there is still a lot we don’t know, such as how likely male-to-female, female-to-male, or male-to-male sexual transmission is — or if female-to-female sexual transmission is probable. It’s thought that Zika virus can find refuge from the immune system in the testicles, which are a difficult location for a virus to enter — but, by the same principle, entry is also difficult for immune cells. Any virus wily enough to wend its way into the testicles, therefore, can replicate in relative peace. And it seems that this lucky virus can persist in the testicles for at least six months — twice as long as previously thought — and can hitch a ride in semen to find new victims.

Currently, there is no treatment or vaccine for Zika virus, but we can still protect ourselves. In addition to DEET, mosquito nets, window screens, air conditioning, and myriad other mosquito-control strategies, we have one other weapon against Zika virus: condoms, which can reduce transmission risk during oral, vaginal, or anal sex. Pregnant people can use condoms to avoid sexual transmission during pregnancy. And, in light of the spike in chlamydia, gonorrhea, and syphilis rates we’ve seen recently, we should be embracing the condom anyway.

A Zika infection during pregnancy can have devastating effects on a fetus — not just microcephaly and other brain defects, but also impaired fetal growth, hearing loss, and miscarriage. Some researchers expect to see more schizophrenia, ADHD, autism, epilepsy, and bipolar disorder as Zika babies are tracked over time. If you or your partner are not pregnant or at risk for pregnancy, the stakes are lower, as infections usually don’t cause symptoms — though if symptoms do appear, they could include fever, rash, joint pain, and red eyes.

Current recommendations are that anyone who has traveled to a region where Zika virus is endemic should either abstain from sex or use condoms for eight weeks — six months if a man has experienced Zika symptoms. Recently, the CDC advised that pregnant people and their partners stay out of Miami-Dade County in Florida, where local mosquitoes have started carrying Zika virus. Anyone who is pregnant and lives in a Zika zone or whose partner has traveled to a Zika zone should also abstain from sex or use condoms throughout pregnancy, as scientists still don’t know how late in pregnancy the virus can harm the fetus. Even when pregnancy is not an issue, partners who want to avoid sexual transmission can use condoms.

Our legislators opted not to provide the funding needed to combat Zika virus on the home front. Here in Arizona, Sens. John McCain and Jeff Flake voted to tie Zika funding to restrictions on contraception access. Excluding Planned Parenthood from the response to Zika makes no sense: Planned Parenthood is uniquely poised to help members of the marginalized communities most likely to be affected by Zika virus. After recommendations to delay pregnancy or use condoms during pregnancy, the contraceptive services provided by Planned Parenthood are more vital than ever. In limiting the number of providers that can be enlisted in the fight against Zika, Congress is denying their constituents an important resource.

If you think you or your partner might have been exposed to Zika virus, your local Planned Parenthood health center can connect you to local testing sites. If you or your partner test positive for Zika virus, we can help you figure out your next steps. Whether you want to terminate a pregnancy, delay pregnancy, or ensure a healthy pregnancy, Planned Parenthood can help.

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