ATLANTA >> All travelers who come into the U.S. from three Ebola-stricken West African nations will now be monitored for three weeks, the latest step by federal officials to keep the disease from spreading into the country.

Starting Monday, anyone traveling from Guinea, Liberia and Sierra Leone will have to report in with health officials daily and take their temperature twice a day.

The measure applies not only to visitors from those countries but also returning American aid workers, federal health employees and journalists. The Centers for Disease Control and Prevention announced the new step Wednesday.

CDC Director Tom Frieden said monitoring will provide an extra level of safety, on top of the temperature checks and screening that passengers undergo before they leave West Africa and again when they arrive in the United States.

"We have to keep our guard up," Frieden told reporters on a conference call.

The Obama administration has resisted increasing pressure to turn away any visitors from the three countries at the center of the Ebola outbreak, especially after a Liberian visitor to Dallas came down with the disease days after he arrived and died. Instead, they started screening at 5 U.S. airports and on Tuesday said all travelers from West Africa would be funneled to those airports.

The monitoring program will start in six states — New York, Pennsylvania, Maryland, Virginia, New Jersey and Georgia — the destination for the bulk of the travelers from the outbreak region. It will later extend to other states.

Each passenger will be required to provide contact information for themselves as well as a friend. They will be instructed to check for a fever twice a day and report their temperature and any symptoms to health officials daily. Frieden said states will determine how to do that, whether in person, by phone or Skype.

If a traveler does not report in, state or local public health officials can track them down to ensure daily monitoring. How far they can go is up to those officials, CDC officials said.

They will also receive "CARE" kits — which stands for Check and Report Ebola. The kits include thermometer and instructions on what to do if symptoms occur. Also included is a card to present to health care providers if they seek care.

CDC already was telling its own employees and other health professionals working in the outbreak zone to monitor their temperature for 21 days upon return, so Wednesday’s announcement adds another step to their ongoing fever watch. It can take as long as three weeks days to develop Ebola symptoms.

Earlier this year, roughly 150 travelers per day were from the three countries. But it appears there are far fewer now — there are no direct flights and flights to the region have been curtailed. New York’s Kennedy airport — which handles the most traffic from the outbreak zone — has averaged 34 a day since screening began Oct. 11.

The other airports are Washington’s Dulles, Newark’s Liberty, Chicago’s O’Hare and Atlanta’s Hartsfield-Jackson. While a few of the people screened thus far have been taken to the hospital, none had Ebola.

According to an Associated Press-GfK poll released Wednesday, Americans are worried about Ebola spreading here, and many say the government hasn’t done enough to prevent that from happening. The poll found a surprising 9 out of 10 people think it’s very necessary to tighten screening procedures.

Some would go even further: Three-quarters think it’s definitely or probably necessary to prevent everyone traveling from places affected by Ebola from entering the U.S.

On Wednesday, White House spokesman Josh Earnest said the president has been following advice from scientists that a travel ban could do more harm than good. Health officials fear travelers will just find alternate routes, and could enter the country unidentified and spark harder-to-trace outbreaks.

Earnest sidestepped a question about whether the new monitoring measure is a way to avoid a travel ban.

Many health experts agree that a travel ban is a bad idea. But one faulted the CDC for being slow to institute the daily monitoring.

Monitoring can’t stop Ebola from coming in, "but we’ll have a better chance" to quickly identify and isolate cases, said Dr. Richard Wenzel, a Virginia Commonwealth University scientist who formerly led the International Society for Infectious Diseases

Such tracking measures might have made a difference in the case of Thomas Eric Duncan, the Liberian man who became the first person diagnosed with Ebola in the United States, Wenzel said. Duncan wasn’t sick and passed the screening when he left Liberia, and didn’t develop symptoms until days after his arrival in Dallas. He died Oct. 8.

Two nurses who took care of him at Texas Health Presbyterian Hospital were infected; both remain hospitalized.

Maryland’s health secretary said it will depend on individual circumstances how closely the state monitors people. Dr. Joshua Sharfstein said his state’s approach will recognize "that some people who come from West Africa are at a higher risk than others." The CDC isn’t mandating that everyone be monitored in exactly the same way, he said.

Also on Wednesday, an American video journalist who has recovered from Ebola at a Nebraska hospital was heading home to Providence, Rhode Island.

"Today is a joyful day," Ashoka Mukpo said in a statement released by the Nebraska Medical Center in Omaha. He arrived Oct. 6.

The virus has killed more than 4,800 people in West Africa, nearly all in Liberia, Sierra Leone and Guinea. Mukpo caught it while working in Liberia as a freelance cameraman for NBC and other media outlets.

___

Associated Press writers Michael Felberbaum in Richmond and Connie Cass, Alicia Caldwell, Ben Nuckols and Jim Kuhnhenn in Washington contributed to this report.