OMAHA, Neb. >> Officials at an Omaha hospital say an American health care worker who was exposed to Ebola in Sierra Leone has not developed the virus.

The patient arrived in Omaha on Jan. 4 for treatment in the biocontainment unit at Nebraska Medical Center. The hospital said in a news release Monday that the patient will remain in the unit throughout the virus’s 21-day incubation period, which began before he or she arrived at the hospital. A discharge date was not released.

The hospital says the patient doesn’t want to be publicly identified but authorized the condition update.

Nebraska Medical Center treated three people with Ebola last fall. One died and two recovered. One of the survivors, Dr. Rick Sacra, said Monday that he’s returning to Liberia, where he was infected.