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Ebola mystery: Did "cured" man infect his girlfriend?

MONROVIA, Liberia -- A woman who tested positive for Ebola in Liberia last week is dating a survivor of the disease, a health official said Tuesday, offering a possible explanation for how she became the country's first confirmed case in weeks.

Ebola is typically transmitted through contact with the blood, vomit or feces of people who are sick. Survivors of Ebola are not generally considered contagious, but the virus lingers in semen, and so scientists urge survivors not to have sex for three months after recovering. Even though sexual transmission of Ebola has not yet been documented, it may be possible.

The evidence is limited, but research conducted over the years suggests Ebola can remain in a patient's semen for up to 91 days -- much longer than other bodily fluids -- even after a patient has recovered and the virus is no longer detectable in a blood test.

During an Ebola outbreak in 2000, the virus was detected in 1 of 2 semen samples from sick patients and could still be found in testing done 40 days later. In a case cited by the World Health Organization, a lab worker who contracted Ebola on the job was found to have traces of the virus in his semen 61 days after the initial infection. And in the longest known example, researchers say another patient's semen still showed traces of the virus after 91 days.

In the current Liberia case, samples have been taken from the boyfriend for testing, said Dr. Francis Kateh, acting head of Liberia's Ebola Case Management Team. The woman tested positive for Ebola on Friday, and her case has caused concern because she didn't seem to be linked to any of the people on an Ebola contacts list and said she did not travel to an infected country.

The patient is now being treated at the Monrovia Medical Unit, a U.S.-built field hospital staffed by health workers from the U.S. Public Health Service, said Kate Migliaccio, a spokeswoman for the service.

The case deflated hopes that Liberia's outbreak might soon be declared over. Liberia has seen more than 4,300 of the more than 10,000 deaths in the West African Ebola outbreak. But since it discharged its last case on March 5, it was counting down the 42 days that a country must wait before being declared Ebola-free.

"It means that we must keep up the prevention more aggressively," President Ellen Johnson Sirleaf told state radio. "It's one person that is being properly traced so that the disease does not spread."

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