The Centers for Disease Control and Prevention and State Department are helping to privately transport to the U.S. additional Americans who may have been exposed to Ebola virus in Sierra Leone, CDC said in an update Saturday. Four individuals will be placed in quarantine at the University of Nebraska Medical Center in Omaha. "In the unlikely instance that one of them does develop symptoms, we would take them to the [hospital’s] Biocontainment Unit immediately for evaluation and treatment,” said Phil Smith, M.D, the unit’s medical director. Other returning individuals will be near the National Institutes of Health in Bethesda, MD, or Emory University Hospital in Atlanta, CDC said. They will follow CDC’s recommended monitoring and movement guidelines during the 21-day incubation period, including direct active monitoring and appropriate voluntary self-isolation, and will be transported to an Ebola treatment center for evaluation and care if they show symptoms, the agency said. The returning Americans may have been exposed to the virus through, or in a manner similar to, a U.S. health care worker who recently tested positive for Ebola virus while volunteering in Sierra Leone, CDC said. That patient is in critical condition at NIH Clinical Center in Bethesda.