The White House said Friday it had no plans to introduce travel bans to stop Ebola reaching the United States, after a patient who later fell ill with the disease made it to Texas.
"There is no consideration of a travel ban at this point," said White House spokesman Josh Earnest.
"There is in place a very sophisticated, multi-layered screening system ... to ensure that the traveling public is safe," said Earnest.
"Those screening protocols begin at the point of departure in West Africa."
The protocols are intended to ensure that passengers showing symptoms of Ebola do not board aircraft.
Earnest also told reporters on Air Force One that customs and border control officers in the United States had been trained to identify travelers showing signs of Ebola when they land.
President Barack Obama's spokesman stressed that Thomas Eric Duncan, the patient who traveled from Liberia to Texas, had not been sick when he flew home, so was not then a danger to fellow travelers.
"There is no one who is suggesting that this individual was exhibiting symptoms of Ebola when he flew from West Africa to the United States.
"That would explain ... why the traveling public is not at risk as a result of his travel. It also explains why he was not stopped in the screening process," Earnest said.
The symptoms of Ebola include fever, vomiting and diarrhea. Those who are sick can only infect others who come in close contact with their bodily fluids.
Earnest also said that, despite the case in Texas and news that a man had been admitted to hospital in the Washington area with Ebola-like symptoms, there was no danger to the wider US population.
"The risk of an Ebola outbreak in the United States is very low," Earnest said. "Ebola is not like the 'flu, you can't catch it through the air."
Obama will get a briefing on Monday with his national security team on the progress in the fight against the epidemic, to which he has committed 3,000 US troops.