U.S. health officials now say that the Ebola virus can be transmitted when survivors of the disease have unprotected sex and could even occur many months after being declared free of the virus.

In a report published on Friday, the Centers for Disease Control and Prevention detailed a case of a 44 year old Liberian woman who they believe contracted Ebola through sexual intercourse with an Ebola survivor.  The man in question developed the virus last September and was discharged a month later.  The woman contracted the virus in March, a week after having sex with the man, and died.

Scientists had previously believed that the Ebola virus could remain in semen for up to about three months after being infected and cured, although suspected cases have been few and difficult to isolate.

"We have suspected that having sexual contact with survivors could be a potential way for people to become infected," says Dr. Barbara Knust, an epidemiologist and Ebola expert at the CDC. "Prior to this outbreak we did have messages given to male survivors to abstain from sex for three months and they were provided condoms."

Now, however, the CDC has altered its recommendations.

"Until more information is known, contact with semen from a male survivor should be avoided. If male survivors have sex (oral, vaginal, or anal), a condom should be used correctly and consistently every time," the MMWR report states.

While the CDC does not believe that male survivors will have to live the rest of their lives this way, they do believe that through further study they will be able to determine the proper length of time men must wait to ensure their partner's safety.

"I want to emphasize that we don't think this is lifelong," says Knust. "We think it's for some period of time for survivors. The thing that's difficult about this public health message is we don't know how many months that is. But it's not like HIV, where those recommendations are lifelong."

Currently there is no evidence that female survivors of Ebola can infect men through contact after they deemed Ebola-free.  That could be because a women's reproduction system has immune cells "constantly patrolling and looking for viruses and bacteria and fungi," as do the bloodstream and most organs, says Knust.  Once a woman has been declared free of Ebola, her immune system would kill off remnants of the virus.

"We're working with the countries involved, and with the World Health Organization, to have testing of semen from survivors as a top priority," says Knust.

Sexual transmission of the disease more than a half a year after the patient was declared Ebola free may just be the first of unexpected findings from the lives of those who survived.  "There will be many things we'll learn from survivors about how people recover and how better to treat and protect people," says Knust.