A woman in Liberia may have contracted Ebola through sex with a man who had recovered from the virus, the US Centers for Disease Control and Prevention say in a report this morning. The finding isn't conclusive, but the CDC says it's certainly suggested by the timeline of events. The woman didn't appear to have come in contact with anyone displaying symptoms of Ebola, and she was found to have the virus in mid-March, just over a week after having vaginal sex with a man who reported symptoms of Ebola back in late September — about five months earlier.

No sign of Ebola was found in a blood sample taken from the man, however tests did detect the virus' presence in a sample of his semen. A partial genome sequence of the virus RNA found in the semen is said to "closely match" a sequence taken from the woman. Earlier research has detected traces of Ebola in semen months after the onset of symptoms, but it's never been seen this long afterward. And while there has been a prior report of Ebola being sexually transmitted in the late ’90s, it was ultimately inconclusive. This instance could become the first confirmed case of sexual transmission, or at least prompt further research that confirms the possibility.

It's notable in this case that the man, who appears to be a survivor of Ebola, was never conclusively determined to have Ebola. After being tested in September when he experienced Ebola-like symptoms, one test came back positive and another came back negative. An additional test taken about a week later also came back negative, and he was discharged from a treatment unit not long thereafter. While that leaves some room for uncertainty, multiple family members that the man lived with or interacted with contracted or appeared to contract Ebola as well.

Because prior research had detected the presence of Ebola in semen months after contraction, both the CDC and the World Health Organization had been recommending that male survivors refrain from sex or use a condom for three months. The CDC is now recommending that people avoid contact with a male Ebola survivor's semen indefinitely, until more is known. If a male survivor has any type of sex, the CDC says that a condom should be used. Additional research is going to be performed on both male and female body fluids to see how the virus persists and if sexual transmission is likely.

In Liberia, where these patients are located, the Ebola epidemic appears to be winding down. Aside from this instance, the country has gone over a month without a confirmed case of Ebola. The US is starting to pack up, shutting down a treatment center, and the country may be nearing a declaration of being Ebola-free, according to the Associated Press. Liberia has had over 4,600 deaths from Ebola since the virus first broke out there in March, 2014.