"All of them have signed up to leave their homes and their loved ones to head straight into the heart of the Ebola epidemic," news agency quoted Obama as saying.

"They do this for no other reason than their own sense of duty. We need to call them what they are, which is American heroes."

Obama noted that those healthcare workers should be "treated with dignity and with respect", apparently criticising mandatory quarantine policies for "high-risk" returning individuals that have been put in place by New York, New Jersey and other US states.

Obama made the remarks at the White House after meeting with a number of healthcare workers who have returned from the front line of the fight in West Africa.

He stressed that with or without travel bans and quarantines, no one could promise that there would not be any more cases in US or any place else.

"So yes, we are likely to see a possible case elsewhere outside of these countries," he said. "Because that's the nature of today's world, we can't hermetically seal ourselves off."