As the Ebola outbreak continues to rage in West Africa, a black market is emerging dealing in the sale of the blood of Ebola survivors.

World Health Organization Director-General Margaret Chan referred to the development earlier this month, saying her group has brought the matter to the attention of local governments and is working to "stamp out any black market activity."

The blood from Ebola survivors is considered valuable because it contains antibodies against the deadly virus. The belief is that transfusions with the blood could either help Ebola patients fight the infection, or give healthy people immunity.

The WHO said earlier this month that doctors should consider using Ebola survivor blood as a treatment, at least until better treatments emerge.

Recently, a 51-year-old American aid worker named Rick Sacra received a blood transfusion from Dr. Kent Brantly, another American aid worker who survived Ebola. Sacra has now recovered, though it's not clear how much of a role the transfusion played.

Bioethicists say selling the blood of Ebola survivors is rife with ethical -- and safety – concerns.

Nancy Walton, an associate professor of nursing and bioethicist at Ryerson University, says it's important to note there is little hard evidence of the effectiveness of "convalescent serum," as such blood products are called.

There was a study conducted almost 10 years ago in which eight Ebola patients were given the blood of recovering patients; seven of those eight survived. But Walton notes that doesn't mean the transfusions were the reason they recovered.

"The difficulty in deciding whether it was the magic bullet that cured these patients is they got very good medical care, over and above other patients," Walton said.

There are always risks inherent from getting blood products, Walton notes, but when you add the black market, those risks increase substantially.

Patients buying such blood could expose themselves to other pathogens, such as HIV or hepatitis. It's also possible such transfusions might result in an even worse case of Ebola. And then there's the chance that the blood they buy will not be from recovering Ebola patients at all.

"There's no quality control and there's a huge opportunity for exploitation based just on how desperate these people must be," Walton said.

What's more, treating patients this way means there's no opportunity for Ebola researchers to collect data on the treatment's outcome, Walton says.

Some may say data-collecting is not as important as getting help to people who need it desperately, but Walton disagrees.

"With such limited resources and such urgency and desperation, it really is very important to collect data, to push forward attention to things that work and pull away attention from initiatives that are either unsafe or ineffective."