It was not entirely unexpected that emerging Zika virus could transmit sexually — as it has now done in the first case acquired in the U.S. — but it jolted a public health narrative that was primarily focused on mosquitoes, pregnancy, and birth defects.
The case was reported Feb. 2, 2016, in Dallas, as a man who acquired the virus in Venezuela transmitted it to a female sex partner upon return to the U.S. The partner reported illness despite not having left the country and residing in an area where mosquito transmission has not been reported. On the same day, the Dallas County Health and Human Services (DCHHS) department received confirmation from the CDC of a second Zika virus case, “an ill individual” who had “recently traveled to Venezuela and was diagnosed with the virus upon returning to Dallas County.” Citing medical confidentiality, health officials gave no other details.
Playing catch-up in a manner similar to the first case of Ebola transmission in the U.S. — which bizarrely also occurred in Dallas — the CDC immediately emphasized condom use while working on more detailed guidelines to prevent sexual transmission.
“Both of the infections with Zika virus were confirmed in the CDC laboratory,” said Tom Frieden, MD, MPH, director of the CDC said at a recent press conference. “The Zika virus continues to be spread primarily through the bite of an infected mosquito. But we know that it can on occasion be spread by sexual contact. We’re also aware of rare examples of transmission through blood transfusion.”
In guidelines issued after the case, the CDC recommends that men who reside in or have traveled to an area of active Zika virus transmission — and who have a pregnant partner — should abstain from sexual activity or consistently and correctly use condoms during sex (i.e., vaginal intercourse, anal intercourse, or fellatio) for the duration of the pregnancy. Pregnant women should discuss their male partner’s potential exposures to mosquitoes and history of Zika-like illness with their healthcare provider.
Men with non-pregnant partners who reside in or have traveled to an area of active Zika virus transmission who are concerned about sexual transmission “might consider” abstaining from sexual activity or using condoms consistently and correctly during sex, the CDC recommended. Couples considering this personal decision should take several factors into account. Most infections are asymptomatic, and when illness does occur, it is usually mild with symptoms lasting from several days to a week; severe disease requiring hospitalization is uncommon, the CDC added.
Zika virus is thought to clear from the blood within about a week of infection, but how long it can survive in semen is currently unknown and under study. A recently published letter reported semen tested positive at 27 days and 62 days after onset of febrile illness. “Although we did not culture infectious virus from semen, our data may indicate prolonged presence of virus in semen, which in turn could indicate a prolonged potential for sexual transmission of this flavivirus,” the authors said.1 Because of reports of detection of Zika virus RNA in saliva and urine,2,3 research is underway in Puerto Rico to determine the persistence of the virus RNA, as well as the presence of infectious virus in saliva, urine, and semen of patients with a laboratory confirmed infection.
REFERENCES
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Atkinson B, Hearn P, Afrough B, et al. Detection of Zika virus in semen [letter]. Emerg Infect Dis 2016 May http://dx.doi.org/10.3201/eid2205.160107.
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Musso D, Roche C, Nhan TX, et al. Detection of Zika virus in saliva. J Clin Virol 2015;68:53–55.
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Gourinat AC, O’Connor O, Calvez E, et al. Detection of Zika virus in urine. Emerg Infect Dis 2015; 21:84–86.
