At the White House, spokesman Josh Earnest said an additional layer of screening would begin at New York's JFK International and the international airports in Newark, Washington Dulles, Chicago and Atlanta. He did not give many details, but another official said separately that the new steps would include taking temperatures and would begin Saturday at JFK.
That official was not authorized to describe the change by name and spoke only on condition of anonymity.
Earnest said the five airports cover the destinations of 94 per cent of the people who travel to the U.S. from the three heavily hit countries in West Africa — Liberia, Sierra Leone and Guinea. He estimate that about 150 people would be checked a day under the new procedures.
A Liberian man with Ebola died Wednesday. He had come to Dallas in late September but did not display obvious signs of having the disease when he entered the U.S.
Also on Wednesday, Homeland Security Deputy Secretary Alejandro Mayorkas said Customs and Border Protection agents are handing out information sheets to travellers with details of what symptoms to look for and directions to call doctors if they become sick within 21 days — the incubation period for Ebola.
Homeland Security agents at airports and other ports of entry already had begun observing travellers coming into the United States for potential signs of Ebola infection.
The fact sheet to be given to arriving travellers says: "You were given this card because you arrived to the United States from a country with Ebola." It tells passengers to "please watch your health for the next 21 days" and to "take your temperature every morning and evening, and watch for symptoms of Ebola," which are listed on the sheet.
Mayorkas said agents would observe all travellers for "general signs of illness" at the points of entry. He spoke at an airport security conference.
The White House, in a fact sheet this week, generally described Customs and Border Protection practices of being alert to passengers with obvious illnesses, but did not specify exactly what would be done to find potentially infected passengers.
The Obama administration has wrestled in recent weeks with what it can do, since arriving passengers may not be symptomatic when they arrive.
Mayorkas said the department was aware of those issues and is "taking a layered approach."
Ebola has killed more than 3,400 people in West Africa and infected at least twice that many, according to the World Health Organization. The virus has taken an especially devastating toll on health care workers, sickening or killing more than 370 of them in the hardest-hit countries of Liberia, Guinea and Sierra Leone — places that already were short on doctors and nurses before Ebola.
President Barack Obama has said the U.S. will be "working on protocols to do additional passenger screening both at the source and here in the United States." Extra screening measures are in effect at airports in the outbreak zones. Departing passengers are screened for fever and asked if they have had contact with anyone infected with the disease.
Dr. Tom Frieden of the Centers for Disease Control and Prevention, said this week that officials are looking at all options "to see what we can do to increase safety of all Americans."