People should avoid contact with semen from Ebola survivors, say U.S. health officials who say a woman in Liberia may have been infected through sexual intercourse with a survivor months after his recovery.

Friday's report from the U.S. Centers for Disease Control and Prevention is based on a review of the case of a 44-year-old woman in Monrovia. Investigators concluded unprotected vaginal intercourse with a survivor is the only explanation of how she was infected, but it's not definitive.

"Previously, CDC and WHO recommended abstinence or condom use for at least 3 months following recovery from
Ebola. However, to prevent transmission of Ebola, contact with semen from male survivors should be avoided," the researchers said.

They advised if male survivors have any form of sex, a condom should be used correctly and consistently every time until more information is known.

The woman's case suggests the Ebola virus persists longer in semen than previously thought and can potentially lead to sexual transmission of the virus. 

The 46-year-old man reported symptoms consistent with Ebola on Sept. 9, 2014, was admitted to an Ebola treatment unit and discharged Oct. 7.

The woman reported having unprotected sex on March 7 with the Ebola survivor. She developed headache, weakness, joint pain and nausea on March 14 and was confirmed as infected with Ebola on March 20.

The man also reported unprotected sex wth a 45-year-old woman around the same time. She later tested negative for Ebola.

The CDC said it plans to do more studies on how long the virus persists in body fluids of male and female survivors and the likelihood of sexual transmission.