“While there is no proven treatment available for Ebola virus disease, whole blood collected from patients in the convalescent phase of infection has been used as an empirical treatment with promising results in a small group of EVD cases,” the guidelines stated.
In the U.S., several patients have received transfusions as part of their treatment. Dr. Kent Brantly, the U.S. physician who contracted Ebola while performing missionary work, reportedly received a transfusion from a recovered patient while in Liberia before returning to the U.S.
Brantly in turn donated his plasma to three other patients—nurse Nina Pham, infected while treating Ebola patient Thomas Eric Duncan in Dallas; Dr. Rick Sacra, who contracted the virus while in Liberia; and freelance journalist Ashoka Mukpo, who got sick while reporting from the region.
Brantly reportedly offered to donate plasma to Duncan, but did not match his blood type. Duncan died Oct. 8.
Dr. Craig Spencer, who is currently being treated for Ebola at a New York City hospital, reportedly received a blood plasma transfusion—also known as convalescent serum or convalescent therapy—from plasma donated by former patient Nancy Writebol, an aide worker who contracted Ebola in Liberia and recovered after receiving care at Emory University Hospital in Atlanta.
What role the transfusions played in those patients recovery really isn't known, however. So, whether convalescent therapy is a truly effective form of treatment is still a subject of debate rather than scientific evidence.
Performed for decades, the basic premise of convalescent therapy involves collecting blood that has developed antibodies directed at fighting Ebola to help reduce the rate of the infection's spread within a sick patient to give the body's immune system time to develop its own defenses.
Scientific evidence to substantiate claims of the therapy's benefit is scarce to nonexistent. The number of patients who have undergone convalescent therapy remains small since transfusion was first used for an Ebola patient in the 1970s, and no clinical trials have ever been developed to determine its efficacy.
Also, experts say such therapy would not be viable for use in the U.S. in the event the country sees a sudden uptick in the number of Ebola cases. That's because there are only a handful of patients in the U.S. who could possibly donate blood plasma for the purpose of creating a stockpile that could be used for future cases.
“There are perhaps six or seven Ebola virus disease survivors in the USA,” said Dr. James Landmark, director of clinical laboratory support services at the University of Nebraska Medical Center, Omaha. “Of whom, three or four are too recently recovered to consider donating plasma or are not sufficiently well enough to donate yet.”
Landmark said blood plasma transfusion would be viable in only a small number of cases.
Whether convalescent therapy would work in West Africa, where hundreds of Ebola survivors are available to donate blood plasma, is unknown, he said, because of the lack of resources available to conduct such treatment on the large scale that would be needed.
Also, transfusions would increase the risk of other infections such as hepatitis and HIV if blood is not properly tested. As Landmark pointed out, under normal conditions, such safety issues can be worked out to lower risk, but in the current situation in West Africa, the time needed to test donated blood may not exist.
Such concerns have not stopped the international community from exploring the widespread use of convalescent serum to address the continuing crisis within the region that has infected more than 10,000 people in the countries of Guinea, Liberia and Sierra Leone since March. Of those infections, more than 4,900 have died.
Transfusions were given to eight patients in the Democratic Republic of Congo during an Ebola outbreak in 1995, of which, seven survived. But it is not known whether convalescent therapy was identified as the cause for the recovery in either the African or U.S. patients or rather the result of aggressive supportive care, or other factors.
“I don't know how efficacious it will be and I don't know if it's really helping or whether it's just serendipity,” said Dr. Lowell Tilzer, professor and chair of the department of pathology and laboratory medicine at the University of Kansas Hospital, Kansas City.
Tilzer estimated that any use of convalescent therapy in West Africa would probably not involve first performing randomized, control trials where one group would receive plasma while another did not in order to study its effectiveness. The need for any kind of treatment is too dire and immediate, he said. Efforts are in the works by some pharmaceutical firms to develop plasma with high concentrations of antibodies from recovered Ebola patients to produce a convalescent serum that could be used for treatment.
But Landmark said such developments would only be a short-term solution that may buy time for an effective vaccine to be developed and mass produced.
“Convalescent plasma from Ebola survivors may help people who are sick, but it won't prevent new cases from occurring,” Landmark said. “Vaccination is the tool we need to stop the epidemic in West Africa.”
Follow Steven Ross Johnson on Twitter: @MHsjohnson
