UPDATE | US to track everyone coming from Ebola nations

ATLANTA (AP) — 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. Passengers already get screened and temperature checks 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 infectious disease days after he arrived and later died. Instead, passenger screening was put in place at 5 key U.S. airports. That was tightened Tuesday to funnel everyone coming from those countries through those airports so all are checked.

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.