The United States on Tuesday tightened restrictions on travelers arriving from the West African countries gripped by an Ebola outbreak, funneling them into five airports with extra health checks.
The Department of Homeland Security ordered passengers whose journeys begin in Guinea, Liberia or Sierra Leone to fly to New York's JFK or Newark airports, Washington Dulles, Atlanta or Chicago.
The new measures go into effect on Wednesday.
There are no direct scheduled flights to the United States from the three countries at the heart of the Ebola epidemic, but travelers from the region can transfer through African and European hubs.
One Liberian with Ebola arrived in Dallas, Texas and infected at least two US health workers before dying, piling pressure on President Barack Obama's government to impose a flight ban.
Health authorities have set up additional screening for passengers at five ports of entry, airports which they say normally handle 94 percent of the travelers arriving from the three worst hit countries.
But Tuesday's order would prevent travelers from Guinea, Liberia or Sierra Leone from transferring to flights to other US airports where they would not necessarily have to pass additional screening.
"If not already handled by the airlines, the few impacted travelers should contact the airlines for rebooking, as needed," Homeland Security Secretary Jeh Johnson said.
"We currently have in place measures to identify and screen anyone at all land, sea and air ports of entry into the United States who we have reason to believe has been present in Liberia, Sierra Leone or Guinea in the preceding 21 days."
The virus has killed more than 4,500 people in West Africa this year, and stoked fears that it could spread beyond the three worst hit countries and become a global threat.
But small outbreaks in Senegal and Nigeria have been halted and, with no new confirmed infections in the United States for six days, authorities are hopeful they have contained the danger here.
Congressman Michael McCaul, a Republican from Texas and chairman of the House Committee on Homeland Security, hailed the DHS move but urged even stricter measures to keep out travelers from West Africa.
"Putting in place travel restrictions and additional screening measures at our airports is a common sense proposal, and I am pleased to see DHS make this announcement," he said in a statement.
"I continue to call on the administration to suspend all visas from Liberia, Sierra Leone and Guinea."