In late July, when it looked like Dr. Kent Brantly wasn’t going to make it, a small news item escaped Liberia. It spoke of Brantly’s treatment — not of the Ebola vaccine, Zmapp, which Brantly later got. But of a blood transfusion. He had “received a unit of blood from a 14-year-old boy who had survived Ebola because of Dr. Brantly’s care,” the missive said.

Now months later, Brantly, who has since recovered from his battle with the virus, has passed on the favor. A 26-year-old Dallas nurse named Nina Pham, who contracted the illness while treating the United States’ first Ebola patient, has received Brantly’s blood. It’s not the first time it has been used to treat Ebola patients. Recovered Ebola victim Richard Sacra got it, as well as U.S. journalist Ashoka Mukpo, who last night said he’s on the mend.

Injecting the blood of a patient such as Brantly, who has recovered from Ebola and developed certain antibodies, is a decades-old but promising method of treatment that, academics and health officials agree, could be one of the best means to fight Ebola. Called a convalescent serum, it might also save Pham, an alum of Texas Christian University.

“Convalescent serum is high on our list of potential therapies and has been used in other outbreaks,” a WHO spokesman told Science magazine in August. “There is a long history of its use, so lots of experience of what needs to be done, what norms and standards need to be met.”

The treatment, in fact, is nearly as old as the disease itself. Peter Piot of the London School of Hygiene and Tropical Medicine, who discovered Ebola in 1976 in Zaire, said the idea even back then was promising. “We had only one possible treatment option in the form of serum from convalescents who had very high levels of antibodies,” he explained to Science. The blood was later used to treat a researcher in Britain who infected himself while drawing blood from an Ebola-infected guinea pig. He survived.

Here's how the virus spreads and how contact tracing works to stop outbreaks. (Gillian Brockell/The Washington Post)

But there are some problems with the treatment. One is the transfer of blood. Even when regulated and monitored, there is risk of spreading other diseases, specifically HIV or hepatitis C. Another issue is uncertainty over the treatment’s efficacy. Scientists haven’t determined a definitive, causal link between recovery and the serum. Then there are problems with the sample size. Despite the virulence of this current bout, Ebola outbreaks are a relatively uncommon thing. They erupt, then disappear. And that’s partly why, scientist Heinrich Feldmann told Newsweek, it has often been too difficult expand the sample size.

That, however, hasn’t stopped researchers from wondering. In 1999, the Journal of Infectious Diseases published an article that analyzed the success of blood transfusions on several patients infected with Ebola during a 1996 outbreak in Kikwit, Congo. The findings suggested something pivotal.

Only one of the eight patients died. “All were seriously ill with severe asthenia, four presented with hemorrhagic manifestations, and two became comatose as their disease progressed,” the study stated. “Only one patient (12.5 percent) died; this number is significantly lower than the overall case fatality rate (80 percent) for the Ebola outbreak in Kikwit and than the rates for other Ebola epidemics.”

One of the patients described in the study was similar to Nina Pham. She was 27-year-old Italian nurse. She had used protective clothing but had perhaps touched her eyes accidentally while wearing contaminated gloves. Soon after, the study said, she developed a fever and other symptoms signaling infection. “She was too weak to stand or sit and had a temperature of 36.5 Celsius…. On June 6, the nurse was transfused with 400 cubic centimeters of blood. Two days later, her appetite improved…. She was discharged from the hospital 21 days after admission.”

Though a later study, according to Science, suggested the patients would have survived anyway, some researchers have continued to believe that the secrets of an Ebola cure lurk in the blood of survivors. “We’re trying to discover what in their immune response enabled them to survive,” Israeli scientist Leslie Lobel, who’s trying to develop a vaccine using those antibodies, recently told Nova. “…The survivors that we follow we view these people as the blessed ones. Those who have the gold in their blood that enabled them survive this serious disease.”

Now, as doctors and scientists scramble to try to find the best way to treat the ballooning number of victims, the World Health Organization says the blood of survivors may be one the best ways. “We agree that whole-blood therapies and convalescent serum may be used to treat Ebola virus disease and that all efforts must be invested into helping affected countries use them safely,” WHO official Marie-Paule Kieny said last month. “This is something that would be ready near term.”

And hopefully it’s something that can save the life of Nina Pham.

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