Earlier this week, the US confirmed its first instance of sexually transmitted Zika virus related to the recent outbreak.
A man returning from Venezuela, where the virus is being locally transmitted, infected his partner in Dallas County, Texas.
To address that concern, on Friday the CDC updated the rough guidelines it has released so far related to Zika and sexual transmission.
CDC director Tom Frieden also said during a call with reporters on Friday that because the link between an observed birth defect and Zika virus appears to be growing stronger, their priority is addressing potential sexual transmission cases involving men who live or have recently visited areas where the virus is being locally transmitted and their partners. That defect is a brain condition called microcephaly, which has raised concerns about pregnant women contracting the virus. Researchers are also looking into the virus’s potential connection to Guillan-Barre Syndrome, a temporary disorder in which the immune system attacks part of the nervous system.
“We are not aware of any prior mosquito borne disease with this outcome of what seems to be occurring with Zika in Brazil. We are quite literally discovering more about it each day. Each day the link becomes stronger.”
Currently, Dallas County is reporting no cases of local transmission via mosquito, which is the main way Zika is spread.
There is no vaccine or treatment for Zika, though the National Institute of Allergy and Infectious Diseases expects early trials of a potential vaccine to start by the end of this year. The virus is transmitted mainly via mosquitoes, which means the best way to prevent Zika infection is to prevent mosquito bites, the CDC says.
Because of the recent sexual transmission, the CDC has updated its Zika guidelines:
- Pregnant women and their male sex partners should discuss potential Zika exposure with the woman’s healthcare provider. This includes any history of Zika-like infection.
- Men with a pregnant sex partner who have travelled or live in areas where the virus is being locally transmitted should consistently and correctly use condoms or abstain from sex during the pregnancy.
- Generally, men who have travelled or live in areas with local Zika transmission who are worried about sexual transmission should consider using condoms or abstain.
- The CDC isn’t sure how long the risk of sexually transmitted Zika lasts, but said they are looking into answering that question. Frieden said Zika virus tends to persist for about a week in blood, but it’s unclear how long it persists in other bodily fluids like semen or saliva. It’s even more unclear if saliva is able to transmit the virus, though there have been reports of Zika virus in saliva samples.
What you need to know about Zika
Once infected, only about one in five people with Zika ever shows symptoms, which most commonly include fever, rash, joint pain, and red eyes.
Zika is carried by mosquitoes, namely the Aedes aegypti, a tropical bug that’s great at transmitting diseases like yellow fever, dengue, and Zika. They are daytime mosquitoes, which means they bite during the day and like hanging out in warm, damp, heavily-populated locations.
Although the Zika virus is mostly transmitted when a mosquito bites a human infected with the virus, then goes on to bite another human, some rare cases of sexual transmission via semen have been documented in the past.
In December 2013, during a Zika outbreak in French Polynesia, a patient that was seeking treatment for hematospermia (blood in the semen) was found to have Zika in his semen. And a 2011 paper documents a man who unwittingly infected his wife with Zika after they had sex upon his return from Senegal where he was studying the mosquitoes responsible for Zika transmission.
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