The head of the Centers for Disease Control and Prevention moved Sunday to ease fears over the return of two medical missionaries infected with Ebola, agreeing that the deadly virus is scary but insisting that an outbreak is highly unlikely in the U.S.
CDC Director Tom Frieden, making the rounds on the Sunday news shows, said U.S. public health protocols are far more stringent and effective than those in West Africa, where at least 729 people have died in the worst Ebola outbreak in history.
"Ebola is a scary disease because it's so deadly," Dr. Frieden said on CBS-TV's "Face the Nation." "The plain fact is, we can stop it from spreading in hospitals, and we can stop it from spreading in Africa, which is really the source of the epidemic and where we're surging our response."
He added, "I don't think it's in the cards that we would have widespread Ebola in this country."
Still, news of the first person infected with the deadly virus to reach U.S. soil touched off alarms on social media. Fueling public interest in pandemics in recent years are fictional and new-journalism books such as "The Hot Zone" and "The Stand" and films including "Contagion" and "12 Monkeys."
Billionaire businessman Donald Trump has posted repeated warnings on Twitter against bringing back the missionaries.
"Stop the EBOLA patients from entering the U.S. Treat them, at the highest level, over there," Mr. Trump wrote in one tweet that ended with an all-capital-letters bellow that, "the United States has enough problems!" More than 1,100 users had retweeted that by Sunday afternoon.
Dr. Frieden said Sunday that the outbreak in Africa has been spread through hospitals with improper infection control practices and by people touching the bodies of those who have died of Ebola during burial rituals. Another 1,323 cases have been diagnosed in Guinea, Liberia and Sierra Leone.
Ebola is spread by direct contact with saliva, blood, urine, vomit and other bodily fluids, but the virus cannot be spread by airborne means, as the most contagious diseases such as the flu can be.
"When patients are exposed to Ebola but not sick, they cannot infect others," Dr. Frieden said. "It doesn't spread casually, and it doesn't spread from someone who's not sick."
The incubation period for the disease is eight to 21 days, and public health officials have quarantined Americans returning from the affected region to ensure that they don't show symptoms, said Dr. Toby Cosgrove, head of the Cleveland Clinic.
Video footage shows that Dr. Kent Brantly was able to walk Saturday from an ambulance to the Emory University Hospital in Atlanta. He contracted Ebola in Liberia during his work through the Christian relief organization Samaritan's Purse.
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The decision to bring the two missionaries stateside was made not by public health officials but by organizers at Samaritan's Purse, Dr. Frieden said.
"He was coming home. The organization that sent him to Africa made the decision to bring him home," said Dr. Frieden. "He's an American citizen, and what our role is in public health is to make sure that if an American is coming home with an infectious disease, we protect others so that they don't spread it."
Dr. Brantly, who was covered in protective clothing as he exited the ambulance, was placed in a special isolation unit at the hospital's infectious disease division after landing at Dobbins Air Reserve Base in Georgia.
Health care worker Nancy Writebol, also infected with the virus, is slated to arrive this week at Emory Hospital.
Mr. Brantly's wife, Amber Brantly, released a statement at the weekend on the Samaritan's Purse website saying, "I spoke with him, and he is glad to be back in the U.S."
"I am thankful to God for his safe transport and for giving him the strength to walk into the hospital," she said in the statement. "Please continue praying for Kent and Nancy - and please continue praying for the people of Liberia and those who continue to serve them there."
There is no cure for Ebola, but patients can recover, especially if they were in good health to begin with and receive effective medical care, said Dr. Frieden on NBC-TV's "Meet the Press."
"Ebola can be deadly, but in people who are healthy, the case fatality rate may be lower than the one that we're usually quoting," said Dr. Frieden. "People like this doctor are much healthier going in than many of the people who are unfortunately still getting Ebola in Africa."
Dr. Cosgrove said the footage showing Dr. Brantly walking was "a terrific sign."
"People spread the disease most when they're sick, which is a good thing, and it looks to me like he's now in the recovery phase or has been able to handle it," said Dr. Cosgrove on NBC-TV's "Meet the Press."
Franklin Graham, president of Samaritan's Purse, released a statement saying, "We thank God that they are alive and now have access to the best care in the world."
"We are extremely thankful for the help we have received from the State Department, the CDC, the National Institutes of Health, WHO and, of course, Emory Hospital," Mr. Graham said.
Still, skepticism remains in some quarters, especially because the CDC came under fire last month after vials containing the smallpox virus from 1972 were found in a storage room. But Dr. Frieden said the organization has moved to tighten its laboratory controls.
The best way to prevent an outbreak on U.S. soil or anywhere else is to contain the virus in West Africa, he said, adding that international health efforts to stop previous outbreaks of Ebola have been successful.
"To really protect ourselves, the single most important thing we can do is stop it at the source in Africa," said Dr. Frieden. "That's going to protect them and protect us."