Jeremy Writebol holds a photograph of his mother and father before an interview with a reporter in Wichita, Kan., Sunday, Aug. 3, 2014. Jeremy is the son of Nancy Writebol, a missionary stricken with Ebola. Nancy Writebol is expected to fly Tuesday to the U.S. for treatment, following a colleague who was admitted over the weekend to Emory University Hospital's infectious disease unit. (AP Photo/Orlin Wagner)The Associated Press
A plane taxies after arriving at Dobbins Air Reserve Base in Marietta., Ga., Saturday, Aug. 2, 2014. Officials at Emory University Hospital in Atlanta expect an American who is infected with the Ebola virus to be transported for treatment today. (AP Photo/John Bazemore)The Associated Press
Hospital workers pass police officers guarding an entrance to Emory University Hospital after an ambulance arrived transporting an American that was infected with the Ebola virus, Saturday, Aug. 2, 2014, in Atlanta. A specially outfitted plane carrying Dr. Kent Brantly from West Africa arrived at a military base in Georgia. Brantly was taken to the Atlanta hospital. Another American with Ebola is expected to join him at the hospital in a few days. (AP Photo/David Goldman)The Associated Press
Dr. Kent Brantly and his wife, Amber, are seen in an undated photo provided by Samaritan's Purse. Brantly became the first person infected with Ebola to be brought to the United States from Africa, arriving at at Emory University Hospital, in Atlanta on Saturday, Aug. 2, 2014. Fellow aid worker Nancy Writebol was expected to arrive in several days. Experts say Emory University Hospital is one of the safest places in the world to treat someone with Ebola, the virus that has killed more than 700 people in Africa. (AP Photo/Samaritan's Purse)The Associated Press
ATLANTA – An American missionary with Ebola is getting better and has received the second dose of an experimental treatment, according to the aid organization she works for in West Africa's Liberia.
Nancy Writebol is expected to be flown to Atlanta's Emory University Hospital on Tuesday, where she will join another U.S. aid worker, Dr. Kent Brantly, in a special isolation unit. Brantly, who was flown to the hospital Saturday, also received the experimental treatment before he left Africa.
The two Americans worked at an Ebola clinic in Liberia, one of three West Africa countries struggling to contain an outbreak of the deadly disease in West Africa. Health care workers are among the most vulnerable because of their close contact with patients.
Writebol, 59, has been in isolation at her home in Liberia since she was diagnosed last month. She's now walking with assistance and has regained her appetite, said Bruce Johnson, president of SIM USA, the Charlotte, North Carolina.-based group that she works for in Africa.
Johnson was hesitant to credit the treatment for her improvement. Brantly's condition has also improved.
"Ebola is a tricky virus and one day you can be up and the next day down. One day is not indicative of the outcome," he said. But "we're grateful this medicine was available."
The experimental treatment is made by Mapp Biopharmaceutical of San Diego, with funding from the government. The treatment is aimed at boosting the immune system's efforts to fight off the virus. It is made from antibodies produced by lab animals exposed to parts of the Ebola virus.
It's impossible to know what if any role the experimental treatment played in the Americans' improvement — they could have improved on their own, as others who survived Ebola have done.
There is no vaccine or specific treatment for Ebola, but several are under development. Brantly, who works for the international relief group Samaritan's Purse, also received a unit of blood from a 14-year-old boy, an Ebola survivor, who had been under his care, according to the group.
In the meantime, dozens of African heads of state were in Washington on Monday for the opening of the U.S.-Africa Leaders Summit, a three-day gathering hosted by President Barack Obama. Among the stated purposes: discussing how to help African nations overcome systemic challenges, including disease.
Ebola is considered one the world's deadliest disease, and about 60 percent of the people who have gotten sick in the current outbreak in West Africa have died. More than 1,600 people have been stricken, killing at least 887 of them in Liberia, Guinea, Sierra Leone and Nigeria.
A Liberian government official has confirmed that a medical evacuation team is scheduled to fly back to the United States early Tuesday with Writebol. Emory said last week that she would be treated there, along with Brantly.
Emory boasts one of the nation's most sophisticated infectious disease units. Patients are sealed off from anyone not in protective gear. Lab tests are conducted inside the unit, ensuring that viruses don't leave the quarantined area. Family members see and communicate with patients through barriers. Ebola is only spread through direct contact with an infected person's blood or other bodily fluids, not through the air.
Writebol and her husband, David, had been in Liberia since last August, sent there by SIM USA and sponsored by their home congregation at Calvary Church in Charlotte.
At the clinic, Nancy Writebol's duties included disinfecting doctors and nurses entering or leaving the Ebola treatment area. Their pastor, the Rev. John Munro, said David Writebol had administrative and technical duties.
The couple has been involved in foreign missions for 15 years, spending five years in Ecuador and nine years in Zambia, where Munro said they worked in a home for widows and orphans.
"Her husband, David, told me Sunday her appetite has improved and she requested one of her favorite dishes - Liberian potato soup — and coffee," Johnson said.
The Writebol's son, Jeremy, after talking with his father Sunday, said it's clear his mother "is still suffering," but said the family remains optimistic.
Officials at the U.S. Centers for Disease Controls and Prevention, also in Atlanta, say they've gotten some blowback for bringing Ebola cases to an American hospital. But Dr. Tom Frieden, CDC director, emphasized again Sunday that there is no threat to the public in the United States.
Hegeman reported from Wichita, Kansas. Associated Press writer Krista Larson in Dakar, Senegal and Medical Writer Mike Stobbe contributed from New York.
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