WASHINGTON >> Fending off demands to ban travel from Ebola-stricken West Africa, the Obama administration instead tightened the nation’s defenses against Ebola by requiring that all arrivals from the disease-ravaged zone pass through one of five U.S. airports.

The move responds to pressure from some Congress members and the public to impose a travel ban on the three countries at the heart of the Ebola outbreak, which has killed over 4,500 people, mostly in Liberia, Guinea and Sierra Leone, since it emerged 10 months ago.

Beginning Wednesday, people whose trips began in Guinea, Liberia or Sierra Leone must fly into one of the five U.S. airports performing fever checks for Ebola, the Homeland Security Department said.

Previously, the administration said screenings at those airports covered about 94 percent of fliers from the three countries but missed a few who landed elsewhere.

There are no direct flights from those nations into the U.S; about 150 fliers per day arrive by various multi-leg routes.

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.”

Since screening started Oct. 11 at New York’s Kennedy airport, 562 people have been checked at the five airports, according to Homeland Security. Of those, four who arrived at Washington’s Dulles airport were taken to a local hospital. No cases of Ebola have been discovered.

The other airports are Newark’s Liberty, Chicago’s O’Hare and Atlanta’s Hartsfield-Jackson.

Homeland Security officials at the airports use no-touch thermometers to check for fever, which can be a symptom of Ebola infection. People who have been infected with the virus may not develop a fever and illness for up to 21 days, however.

As the U.S. closed a gap in its Ebola screening, an Ebola-free African country said it would begin checking visiting Americans for the disease.

Rwanda’s health minister said Tuesday that travelers who have been in the United States or Spain — the two countries outside of West Africa that have seen transmission during the Ebola outbreak — will be checked upon arrival and must report on their health during their stay.

No Ebola cases have been reported in Rwanda, which is in East Africa. The U.S. Embassy in Rwanda said that country is banning visitors who have recently traveled to Guinea, Liberia, or Sierra Leone, the three countries at the heart of the outbreak, as well as nearby Senegal, which had a single case

The change in U.S. policy falls short of demands by some elected officials and candidates for a ban on travel from the West African outbreak zone. Sen. Chuck Schumer, D-N.Y., described the action as an “added layer of protection against Ebola entering our country.”

The change comes as the Centers for Disease Control and Prevention works to spread the word about its new protective guidelines for medical workers. The advice, released Monday night, had been sought by health workers after two Dallas nurses were infected while caring for a Liberian traveler, the first person diagnosed with the virus in the United States.

The CDC said it’s still unclear exactly how the nurses were infected, but the stronger rules will provide better protection. CDC officials demonstrated the recommended techniques Tuesday at a training session for several thousand health care workers in New York City.

New York Gov. Andrew Cuomo urged the health-care workers there to use their training to educate their families and communities.

“Keep the anxiety down. Keep the fear down,” he said.

Earlier CDC guidelines allowed hospitals some flexibility to use available covering when dealing with suspected Ebola patients. The new guidelines set a firmer standard, calling for full-body garb and hoods that protect worker’s necks; setting rigorous rules for removal of equipment and disinfection of hands; and calling for a “site manager” to supervise the putting on and taking off of equipment.

They also call for health workers who may be involved in an Ebola patient’s care to repeatedly practice and demonstrate proficiency in donning and doffing gear — before ever being allowed near a patient.

The CDC cannot require hospitals to follow the guidance; it’s merely official advice.

The mother of Amber Vinson, one of the sick nurses, said her daughter is “doing OK, just trying to get stronger” at Emory University Hospital in Atlanta. Debra Berry said she was glad about the new rules, even though they came too late to help her daughter and fellow Dallas nurse Nina Pham, who is being treated at the National Institutes of Health outside Washington. Pham’s condition has been upgraded from fair to good, the NIH said late Tuesday.

“It should help ensure that no one has to endure what Amber and what Ms. Pham have had to go through these weeks, and their families,” Berry told ABC News.

In Rwanda, a Ministry of Health document said all travelers from the U.S. and Spain would have their temperatures taken upon arrival and those with fevers would be denied entry.

Dr. Agnes Binagwaho, Rwanda’s health minister, said Tuesday the travelers will be required to fill a detailed form upon arrival at border entry points.

“It is definitely extra work for us,” Bingwaho said. “We have to ensure that all citizens or any other travelers arriving from the above-mentioned countries, including the U.S., have to be screened in an extra careful manner and follow up on them during their stay.”

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Associated Press writers Mike Stobbe in New York and Emily Schmall in Dallas contributed to this report.