A US doctor infected with the Ebola virus "seems to be improving," a top US health official said Sunday after the aid worker was flown back to the United States from Africa for treatment.
Undated photo obtained July 30, 2014 from charity Samaritan's Purse shows Dr Kent Brantly near Liberia's capital Monrovia where he contracted Ebola while treating patients
Kent Brantly, one of two American aid workers infected with the deadly virus in West Africa, is being treated in an isolation unit at Emory University hospital in Atlanta.
"It's encouraging that he seems to be improving. That's really important, and we're hoping he'll continue to improve," said Tom Frieden, the director of the Atlanta-based Centers for Disease Control.
"But Ebola is such a scary disease because it's so deadly," he added, speaking on CBS's Face the Nation.
More than 700 people have died in West Africa during the current outbreak. Since the virus emerged in 1976 it has killed two-thirds of those infected.
US administration officials insisted the latest outbreak would not affect a three-day US-Africa summit that begins in Washington Monday, with the participation of nearly 50 of the continent's leaders and their entourages.
"We'll be monitoring the situation very closely," Valerie Jarret, a senior advisor to President Barack Obama, said on CBS's Face the Nation. "But we're confident that the summit will be a huge success and we will, obviously, take the precautions that are necessary."
Frieden stressed that despite the spread of the virus in West Africa, it can be contained.
"The plain fact is, we can stop it. We can stop it from spreading in hospitals and we can stop it in Africa," Frieden said.
"In fact, we have stopped every previous outbreak, and I'm confident we can stop this one," he said.
Frieden said a surge of 50 public health experts in the three countries affected by the outbreak would be deployed in the next 30 days.
Brantly's wife Amber asked for people to pray for her husband's recovery and that of those stricken with the virus in Liberia.
"I spoke with him, and he is glad to be back in the US. I am thankful to God for his safe transport and for giving him the strength to walk into the hospital," she said in a statement.
Christian missionary worker Nancy Writebol is expected to be airlifted back to the United States in the coming days by the same method as Brantly.
- Family 'not at risk' -
Frieden said Brantly's wife and two children visited the doctor in Liberia but were not thought to have been at risk.
"It doesn't spread casually and it doesn't spread from someone who's not sick," Frieden said. "And our understanding is that they did not have contact with him when he was sick. "
While Frieden acknowledged it was "possible" the US could see further cases of Ebola if an infected indivdiual entered the country after returning from the affected region, authorities were confident the disease would not gain a foothold.
"We know it's possible that someone will come in," he said. "If they go to a hospital and that hospital doesn't recognize it's Ebola, there could be additional cases.
"But I don't think it's in the cards that we would have widespread Ebola in this country because the way it spreads in Africa is really two things. First, in hospitals where there isn't infection control. And second, in burial practices where people are touching the bodies of people who have died from Ebola. So it's not going to spread widely in the US."
In a separate development, a retired US doctor working in Liberia as part of an international team revealed he had placed himself in voluntary quarantine after returning to the United States on July 25.
Alan Jamison, 69, told CNN he had shown no symptoms of the virus but had chosen to live in seclusion in Morristown, Tennessee as a precaution for a 21-day period.