Donated blood from an American Ebola patient who recovered from the virus has been used to treat another patient, Samaritan’s Purse has confirmed with FoxNews.com.

The humanitarian organization confirmed that a unit of Dr. Kent Brantly’s “convalescent serum”— which could be described as similar to blood plasma— has been donated to treat American Rick Sacra. Brantley and Sacra have the same blood type. Officials at Nebraska Medical Center confirmed with FoxNews.com that 51-year-old Sacra received two transfusions at the hospital since Brantly made the donation on Friday.

The evidence is mixed for using infection-fighting antibodies from survivors' blood for Ebola, but without any licensed drugs or vaccines for the deadly disease, some say it's worth a shot.

"This is something that's fairly simple to do," Dr. Peter Piot, director of London's School of Hygiene and Tropical Medicine and the co-discoverer of the Ebola virus, told the Associated Press.

Sacra’s wife, Debbie, released a statement on Thursday afternoon, saying her husband is steadily improving and his condition quickly turned around after he was admitted to the hospital on Friday.

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“We are hoping most of all that what is learned from Rick's and his colleagues' illness can open up viable possibilities for the treatment of Ebola in West Africa where the suffering is now extending far beyond the victims of the virus itself,” she said.

The World Health Organization (WHO) said last week it would accelerate the use of experimental treatments and vaccines to contain the epidemic in West Africa. More than 200 Ebola experts met to discuss treatment options for patients, and said survivors’ blood could be used immediately to treat patients.

Officials said evidence for whether blood from survivors can help patients is mixed. Thousands have survived the virus, which has about a 50 percent death rate.

Doctors had previously said they were considering using blood serum from an Ebola survivor to treat Sacra, a Massachusetts doctor, who became the third of four Americans to contract the virus while working in Liberia.

Brantly, 33, who contracted the virus while working in Liberia in July, received a vial of blood from an Ebola survivor before being evacuated to an Atlanta’s Emory University Hospital isolation unit. Brantly was also given the experimental drug ZMapp, though it is unknown what effect it had on his recovery.

Nancy Writebol, 51, who also contracted the virus in Liberia was treated with ZMapp at Emory and has since recovered.

A fourth American patient, who has not been identified, arrived at Emory Tuesday. The WHO would only confirm that a doctor who had been working in an Ebola treatment center in Sierra Leone tested positive for the disease, with the State Department later confirming the patient is American.

Details of the latest patient's treatment are not known, but ZMapp could not have been used. Brantly and Writebol were the first to receive it; it had never been tested on humans. The rest of the limited supply was given to five others.

The Associated Press contributed to this report.