An American doctor who contracted Ebola while treating victims of the deadly virus in Liberia has been discharged from an Atlanta hospital after treatment with an experimental drug.

"Today is a miraculous day," Kent Brantly told reporters. "I am thrilled to be alive, to be well, and to be reunited with my family."

Brantly was given ZMapp, a drug developed by U.S.-based Mapp Biopharmaceutical and used on just a handful of patients across the world suffering from the West African outbreak.

The "secret serum" is what's known as a "monoclonal antibody." As James Hamblin of The Atlantic explains, these substances are created by infecting an animal with the disease in question. Then, scientists harvest antibodies, created by the animals' immune systems, to make the drug. With ZMapp, the antibodies were harvested from Ebola-infected mice.

Doctors aren't completely sure how the drug affected Brantly and Nancy Writebol, another Ebola patient released from Emory on Thursday.

"They are the very first individuals to have received this agent … and frankly we do not know whether it helped them, made no difference, or theoretically, delayed their recovery," Bruce Ribner, medical director of Emory’s Infectious Disease Unit, said.

Brantly is just grateful to be alive.

"As a medical missionary, I never imagined myself in this position. When my family and I moved to Libera … Ebola was not on the radar," Brantly said. "We moved to Liberia because God called us to serve the people in Liberia.

"In March … we began preparing for the worst. We received the first Ebola patient in June. [After] the use of an experimental drug and the expertise of a healthcare team at [Atlanta's Emory Hospital] … God saved my life," he added.

Three African doctors, also treated with ZMapp in Liberia, have shown remarkable signs of improvement, Reuters reports.



An ambulance arrives with Ebola victim Dr. Kent Brantly, right, to Emory University Hospital, Saturday, Aug. 2, 2014, in Atlanta. AP Photo/ WSB-TV Atlanta

Reuters handout At least 2,473 people have been infected, and 1,350 have died since the Ebola outbreak was identified in remote southeastern Guinea in March. Most places in Africa don't have the sanitation or basic medical knowledge to deal with the ruthless disease.

"You have people saying they don't have food, they don't have water, they need their IV replaced — and you're trying to do all of that," Daniel Bausch, a doctor and associate professor who has treated victims, told Business Insider."I need to wash my hands before I see the patients, and there might be no running water. There [is sometimes] no soap, no clean needles."

The progression of symptoms for Ebola is alarming. Initially, the fever, weakness, muscle pain, headache, and sore throat associated with Ebola could be mistaken for a bad flu.

But soon, that's followed by vomiting, diarrhea, rash, and impaired organ function. A large proportion of those infected also bleed profusely, both internally and externally. Blood often flows from puncture sites (e.g., where IVs have been inserted) and mucous membranes (e.g., the nose, the eyelids).

Ebola is one of at least 30 viruses known to cause this constellation of symptoms, called viral hemorrhagic fever syndrome.





Kevin Loria contributed to this report.