(Adds CDC will send 50 staff to West Africa, statement from Brantly's wife) 
 
 By Rich McKay 
 
 ATLANTA Aug 3 (Reuters) - An American doctor stricken with the deadly Ebola virus while in Liberia and brought to the United States for treatment in a special isolation ward is improving, the top U.S. health official said on Sunday. 
 
 Dr Kent Brantly was able to walk, with help, from an ambulance after he was flown on Saturday to Atlanta, where he is being treated by infectious disease specialists at Emory University Hospital. 
 
 "It's encouraging that he seems to be improving - that's really important - and we're hoping he'll continue to improve," said Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta. 
 
 Frieden told CBS's "Face the Nation" it was too soon to predict whether Brantly would survive, and a hospital spokesman said Emory did not expect to provide any updates on the doctor's condition on Sunday. 
 
 Brantly is a 33-year-old father of two young children who works for the North Carolina-based Christian organization, Samaritan's Purse. He was in Liberia responding to the worst Ebola outbreak on record when he contracted the disease. 
 
 Since February, more than 700 people in West Africa have died from Ebola, a hemorrhagic virus with a death rate of up to 90 percent of those infected. The fatality rate in the current epidemic is about 60 percent. 
 
 Frieden told ABC's "This Week" that the CDC was "surging" its response, and that it will send 50 staff to West Africa "to help stop the outbreak in the next 30 days." 
 
 Amber Brantly, Dr. Brantly's wife, said she was able to see her husband on Sunday and he was in good spirits, and that the family is confident he is receiving the very best care. "He thanked everyone for their prayers," she said in a statement. 
 
 A second U.S. aid worker who contracted Ebola alongside Brantly, missionary Nancy Writebol, will be brought to the United States on a later flight as the medical aircraft is equipped to carry only one patient at a time. 
 
 Standard treatment for the disease is to provide supportive care. In Atlanta, doctors will try to maintain blood pressure and support breathing, with a respirator if needed, or provide dialysis if patients experience kidney failure, as some Ebola sufferers do. 
 
 SECOND MISSIONARY EXPECTED SOON 
 
 Writebol, a 59-year-old mother of two who worked to decontaminate those entering and leaving an Ebola isolation unit in Liberia, was due to depart for the United States overnight on Monday, Liberia's information minister said. 
 
 Writebol's husband, David, who had been living and working in Liberia with his wife, was expected to travel home separately in the next few days, their missionary organization, SIM USA, said in a statement. 
 
 Despite public concern over bringing in Ebola patients, the CDC's Frieden said the United States may see a few isolated cases in people who have been traveling, but did not expect widespread Ebola in the country. 
 
 The facility at Emory chosen to treat the two infected Americans was set up with CDC and is one of four in the country with the ability to handle such cases. 
 
 The Americans will be treated primarily by four infectious disease physicians, and will be able to see relatives through a plate-glass window and speak to them by phone or intercom. 
 
 Frieden said it was unlikely Brantly's wife and children, who left Liberia before he began showing symptoms, contracted the disease because people who are exposed to Ebola but not yet sick cannot infect others. 
 
 The CDC has said it is not aware of any Ebola patient having been treated in the United States previously. Five people entered the country in the past decade with either Lassa Fever or Marburg, both hemorrhagic fevers similar to Ebola. 
 
 President Barack Obama has said some participants at an Africa summit in Washington this week would be screened for Ebola exposure. Frieden said on Sunday there was no reason to cancel the event. 
 
 "There are 50 million travelers from around the world that come to the U.S. each year ... We're not going to hermetically seal this country," he told Fox News Sunday. (Additional reporting by Emma Farge in Dakar; Writing by Doina Chiacu and Cynthia Johnston; Editing by Frances Kerry and Sandra Maler) ||||| This Video Player Requires JavaScript It has come to our attention that the browser you are using is either not running javascript or out of date. Please enable javascript and/or update your browser if possible. 
 
 
 
 
 
 Dr. Kent Brantly, one of the two Americans who contracted Ebola in Liberia, received a dose of an experimental serum before he was flown to the United States for treatment, an aid organization that he works with said Sunday. 
 
 The aid organization, a Christian group called Samaritan’s Purse, said it was grateful for news that Brantly’s condition is improving. Earlier, the group had said there was only enough serum for one dose and that it went to Nancy Writebol, the other American infected. Writebol is to be flown to Atlanta this week and treated at Emory University Hospital, where Brantly is also being treated. There is no known cure for Ebola. Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, has said he does not know what treatment the group may be using. There are several in development. 
 
 Brantly’s wife, Amber, said Sunday that Brantly is in good spirits. She said in a statement that the family was “rejoicing over Kent’s safe arrival” and confident that he is getting the best possible care. 
 
 IN-DEPTH 
 
 SOCIAL 
 
 First published August 3 2014, 2:55 PM
– As the first Ebola patient to arrive in the US recovers in an Atlanta hospital, dozens of US experts are preparing to go to the other way. At least 50 public health experts are being sent to West Africa to help fight the deadliest-ever outbreak of the disease, Centers for Disease Control and Prevention director Thomas Frieden tells ABC. "The single most important thing we can do to protect Americans is to stop this disease at the source in Africa," he says, explaining that the outbreak can be stopped. "We do know how to stop Ebola," he says. "It's old-fashioned plain and simple public health: find the patients, make sure they get treated, find their contacts, track them, educate people, do infection control in hospitals." He says the US won't "hermetically seal" its borders against the disease. More: American doctor Kent Brantly, who is in an isolation ward at Emory University Hospital, appears to be improving, the Guardian reports. There is no cure for the disease, but doctors hope Brantly is healthy enough to pull through. The medical aircraft that brought Brantly to the US can only carry one patient at a time, so a second American infected with the disease won't arrive in the US until tomorrow. reports Reuters. Missionary Nancy Writebol, 59, was infected as she worked to decontaminate people in an isolation ward in Liberia. The aid organization Brantly works for now says he was treated with an experimental serum before he was sent to the US, NBC finds. The Christian group Samaritan's Purse had earlier said there was only one dose of the serum available, and Brantly asked for it to go to Writebol.