Second American with Ebola back in US for treatment

The second American aid worker diagnosed with Ebola in West Africa was brought back to the United States Tuesday for treatment.

Nancy Writebol arrived in a private plane equipped with a unique containment unit at Dobbins Air Force Base near Atlanta Tuesday morning. The 59-year-old missionary from North Carolina was then transported by ambulance to Atlanta's Emory University Hospital, where she joined her colleague Dr. Kent Brantly in a special isolation unit to receive treatment.

Writebol was reportedly "very weak" but getting better. When she arrived at the hospital, she was taken in by a stretcher.

"After ambulance transfer from Dobbins Air Reserve Base in Marietta, Georgia, the patient arrived at Emory University Hospital on Tuesday, Aug. 5 at approximately 1:10 p.m. ET (1710 GMT)," the hospital said in a statement.

"This special isolation unit was previously developed to treat patients who are exposed to certain serious infectious diseases. It is physically separate from other patient areas and has unique equipment and infrastructure that provide an extraordinarily high level of clinical isolation," it said.

Writebol was serving on a joint team in Liberia with Brantly of Samaritan's Purse, an international relief organization, when they both contracted the virus.

Brantly, 33, was brought back by the same medical evacuation plane on Aug. 2 for treatment. Many experts were surprised to see him walk into the hospital.

Brantly's wife, Amber, said in a statement Tuesday that he is recovering.

"I have been able to see Kent every day, and he continues to improve," she said. "I am also thrilled to see that Nancy arrived safely in Atlanta today ... we will walk through this recovery time together."

U.S. media reported both patients have been improving after they received a highly experimental antibody cocktail called ZMapp, supplied by San Diego-based Mapp Biopharmaceutical.

Scientists from California-based Scripps Research Institute said Tuesday they are investigating antibodies to fight Ebola virus, including the three antibodies used to treat the two Americans.

"Professor Erica Ollmann Saphire and Assistant Professor Andrew Ward are studying the structures of these antibodies using techniques called electron microscopy, which creates high- resolution images by hitting samples with electrons, and X-ray crystallography, which determines the atomic structure of crystalline arrays of proteins," the institute said in a statement.

"Through these images, the team will discover exactly how the immune system molecules bind to the Ebola virus and stop it from functioning, a critical step in drug development."

The ZMapp treatment is still in experimental stages and has not yet been approved for use outside the two recent cases. According to Saphire, ZMapp is one of the best antibody cocktails currently known, but there may still be ways to improve it.

Ebola virus can kill up to 90 percent of those who become infected, and the fatality rate in the current epidemic is about 60 percent.

The outbreak, by far the largest in the nearly 40-year history of the disease, has affected 1,603 and killed 887 people this year in four Western African countries -- Guinea, Liberia, Nigeria and Sierra Leone, according to the World Health Organization.