The Ebola virus can remain in semen for longer than previously thought, and so men who survive the disease should always use a condom during sex until more information is known, the Centers for Disease Control and Prevention says.
This new recommendation follows the report of a woman in Liberia who may have contracted Ebola through sex with a man who had survived the disease.
The woman, who developed Ebola in mid-March, had not had contact with anyone with Ebola symptoms, and hadn't traveled to other areas where people have Ebola. But about a week before her symptoms began, she had unprotected sex with a man who had survived Ebola.
Although the man had been declared Ebola-free six months earlier, in October 2014, a sample of his semen taken in late March of this year found genetic material from the Ebola virus. What's more, when researchers looked at part of the genetic sequence of the Ebola virus in the man's semen, this part matched the Ebola virus found in the woman, according to a new report of the case.
The researchers can't say for certain that the woman caught Ebola through sex, but the information they have so far suggest that it's possible, they said.
There has been just one other report of a person who possibly contracted Ebola through sex — the case occurred during a 1995 Ebola outbreak in the Democratic Republic of the Congo — but this report was also not conclusive. [What Are the Long-Term Effects of Ebola?]
Researchers knew that the Ebola virus could survive for months in semen, and have previously recommended that Ebola survivors either abstain from sex or use a condom for at least three months following their illness.
But the new report suggests that the man transmitted Ebola through sex about five months after he recovered, and nearly 200 days after he first showed Ebola symptoms.
"To prevent transmission of Ebola, contact with semen from male survivors should be avoided," the researchers wrote in the report, published today (May 1) in the journal Morbidity and Mortality Weekly Report. "If male survivors have sex (oral, vaginal or anal), a condom should be used correctly and consistently every time until further information is known."
Additional studies are now planned to determine how long the Ebola virus stays in the bodily fluids of survivors, to better understand the risk of Ebola spread through sex, the researchers said.
Still, if Ebola is transmitted through sex, it's not known how often it happens. The Ebola survivor in the report also had sex with another woman during February and March, but she did not contract Ebola, the report said.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.