Dr. Kent Brantly in Liberia before he contracted Ebola. (Courtesy Samaritan's Purse)

[Updated at 6:15 p.m. ET]

Even from his own sickbed in Africa, American physician Kent Brantly continues putting the well-being of others before his own.

Brantly, a medical missionary in West Africa, and fellow American Nancy Writebol both contracted Ebola last weekend. They spent the past several days under quarantine and are struggling to survive.

On Wednesday, an experimental serum arrived in Monrovia, Liberia, but there was only enough dosage for one patient.

SIM missionary Nancy Writebol and her husband, David, have served in Africa for 10 years. (Courtesy photo)

“Dr. Brantly asked that it be given to Nancy Writebol,” said Franklin Graham, president of Samaritan’s Purse, the Christian humanitarian organization Brantly is working for.

Late Thursday, officials at Emory University Hospital near the Centers for Disease Control and Prevention in Atlanta confirmed that one of the two aid workers will soon be brought to a special high-security ward there. The name of the patient was not revealed.

Brantly's gesture of letting Writebol have the serum fits the description of selflessness and sacrifice the 33-year-old’s family back in the U.S. has given.

“Kent prepared himself to be a lifetime medical missionary,” his mother, Jan Brantly, told The Associated Press on Monday. “His heart is in Africa.”

After the merciful move for Writebol, a local family made its own offering to Brantly.

“Dr. Brantly received a unit of blood from a 14-year-old boy who had survived Ebola because of Dr. Brantly’s care,” Graham said in a written statement. “The young boy and his family wanted to be able to help the doctor that saved his life.”

The organization said Brantly, a married father of two young children, took a “slight turn for the worse overnight.” Samaritan’s Purse says Brantly and Writebol, 59, remain in grave but stable condition.

“Their heroic and sacrificial service — along with the entire team there — is a shining example of Christ’s love in this crisis situation,” Graham said.

Confirmed, probable, and suspect cases and deaths from Ebola as of July 27. (WHO)

There is no known cure or vaccine for Ebola. Details about the serum weren't immediately available on Thursday.

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Writebol, a longtime missionary from Charlotte, N.C., had been working as a hygienist who decontaminated patients entering and leaving the Ebola isolation ward of the local hospital. Officials are still investigating how the two Americans contracted the disease, which has a 60 to 90 percent mortality rate.

The 2014 Ebola outbreak is the worst ever recorded and has now claimed more than 700 lives in West Africa. On Thursday, U.S. health officials warned Americans to not travel to the hardest-hit areas.

Humanitarian groups such as the U.S. Peace Corps and others are evacuating all volunteers. In a statement, Samaritan’s Purse said all its nonessential personnel should be evacuated to their home countries by this weekend.

“None of the evacuating staff are ill and the World Health Organization and CDC continue to reiterate that people are not contagious unless they begin showing symptoms,” the organization said in a statement. “Following their evacuation, Samaritan’s Purse will work with staff to monitor their health.”

(Editor's Note: Nancy Writebol's age has been corrected from previous versions.)

Follow Jason Sickles on Twitter (@jasonsickles).