Why Treating Ebola With An Experimental Serum Might Help
MELISSA BLOCK, HOST:
Two American medical missionaries who contracted Ebola in Liberia received an experimental serum to treat the disease. That's according to the aid group they were working with, Samaritan's Purse. NPR's Richard Harris has this story about what serums are and their long and surprisingly successful history.
RICHARD HARRIS, BYLINE: When doctors talk about serum to treat disease, what they're talking about is antibodies taken from the bloodstream which can neutralize a specific germ. Dr. Arturo Casadevall at the Albert Einstein College of Medicine says, absent a proven drug to treat Ebola, serum is the next best thing.
ARTURO CASADEVALL: I think the idea makes perfect sense.
HARRIS: In fact, it has a rich history. Back in the late 19th century, doctors discovered that the blood taken from someone who had fought off a disease contains protective proteins called antibodies. The clear part of the blood - the serum - could be injected into somebody else, and the disease-fighting ability would be passed along.
CASADEVALL: And about 40 years, that was the only way to treat many infectious diseases. In those days, the serum is made in horses, and it was transferred to people. And it was used to treat pneumonia, meningitis and some other diseases, and it was very effective.
HARRIS: Antibiotics ended up replacing this treatment for most diseases, though they're still used in medicine today. Dr. E. Richard Stiehm is at the UCLA School of Medicine.
E. RICHARD STIEHM: For example, if you step on a nail and are exposed tetanus, and you've never been vaccinated, you can get something called tetanus immune globulin, which is antibodies from other people that work immediately.
HARRIS: There have been a few previous attempts to use this technique with Ebola. A study from 1995 reported on eight Ebola patients who had been given blood transfusions from people who had recovered from the disease. Seven of the eight survived.
CASADEVALL: But it's a now impractical thing because these patients that have convalesced from Ebola are very rare and hard to come by.
HARRIS: Instead, several labs around the world are at work using biotechnology to tailor-make anti-Ebola antibodies called monoclonal antibodies. That includes a Canadian government lab, a collaboration between the U.S. government and scientists in Japan and San Diego-based MAP BioPharmaceuticals. CNN was first to report that MAP BioPharmaceuticals provided the experimental serum that was used to treat the American missionaries who contracted Ebola. U.S. government officials later verified that report.
There are several scientific studies showing that monoclonal antibodies can protect monkeys from Ebola. And Casadevall says, success in animals is likely to mean success in people. But that's not to say this would work perfectly.
CASADEVALL: The thing about antibodies is that they work best if given before infection or shortly after infection. Often, when the disease has set in, antibodies are not that effective. But in some diseases, they are. And the only way to know whether, in fact, they would help individuals who are already ill would be to do the clinical trials.
HARRIS: Those human trials have not yet taken place, so it's not yet clear how well the monoclonal antibodies would work, either as treatment or prevention. Casadevall notes that there's a lot of skepticism of Western doctors in areas where Ebola is breaking out, so testing experimental drug would be a delicate matter.
CASADEVALL: You could imagine that it could initially be used on health care providers who are going to be going into these areas and be infected.
HARRIS: And if it proves useful for them, perhaps the affected population would be more receptive to trying this experimental therapy. Richard Harris, NPR News.
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