There are lots of survivors of Ebola in various parts of Africa who could donate blood with the immune factors needed to fight the disease. This is called "passive immunity", as you get the immunity from donated factors, not by actively producing the factors themselves. It also can be dangerous, the donor may be donating other factors the victim can't handle.
In America, there are only the previous people brought here for treatment who have survived. One of them, Dr. Kent Brantly, says via the news services that they were contacted, & offered to donate blood for Mr. Duncan, but were never called back; presumably their blood type didn't match. I would have hoped that the factors needed to treat Ebola could have been isolated, but apparently medical science is not at that stage yet; they were treating this like any other blood donation, where the types have to match. Mr. Brantly did donate blood to treat Ashoka Mukpo & Dr. Rick Sacra, both being treated in the US. Dr. Sacra has since recovered, says the article I found:
http://www.nbcnews.com/storyline/ebola- ... po-n220811
If the medical systems in Africa were up to it Mr. Duncan would have been better off staying there for a donor. But they're not up to it. They're not treating people via blood donations at all, from what I can find. Although Wikischmoozia says "During a 1995 Ebola virus outbreak in the Democratic Republic of Congo, whole blood from recovering patients, and containing anti-Ebola antibodies, was used to treat eight patients, as no effective means of prevention currently exists, though a treatment was discovered recently in the 2013 Ebola epidemic in Africa. Only one of the eight infected patients died, compared to a typical 80% Ebola mortality, which suggested that antibody treatment may contribute to survival."
And apparently there's no more of the drug, ZMapp, that was used on the other people brought back to the US left. Period. Chilling. Also deadly, for Mr. Duncan.
According to
http://guardianlv.com/2014/08/ebola-zma ... tial-cure/, passive immunity is also used to describe what ZMapp confers. Apparently passive immunity is a very inclusive term.