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. The measure applies not only to visitors from those countries but also returning American aid workers, federal health employees and journalists. 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. If a traveler does not report in, public health officials can track them down. CDC already was telling its own employees and other health professionals returning from the outbreak zone to monitor their temperature. 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. Health officials fear travelers will just find alternate routes and spark harder-to-trace outbreaks. Monitoring can't stop Ebola from coming in, "but we'll have a better chance" to quickly identify and isolate cases, said Dr.