An American health care worker who experienced high-risk exposure to the Ebola virus while working in Sierra Leone arrived at a Nebraska hospital Sunday for observation.

The patient landed in Omaha on Sunday afternoon. Paramedics wearing full-body protective gear drove the patient to the Nebraska Medical Center, which has a specialized biocontainment unit.

Dr. Phil Smith, who leads the unit, said the patient is neither ill nor contagious. He said the patient will be observed for any signs of Ebola throughout the virus' 21-day incubation period, and that "all appropriate precautions" will be taken.

Hospital spokesman Taylor Wilson added that doctors and nurses are wearing full protective gear and taking the same precautions they did when treating patients with Ebola, even though this patient hasn't tested positive.

The Omaha hospital treated three patients with Ebola last fall. Dr. Rick Sacra, who worked at a Liberian hospital, and freelance video journalist Ashoka Mukpo, who also worked in Liberia, both recovered from Ebola after being treated at the hospital. Dr. Martin Salia, who contracted Ebola while working in Sierra Leone, was much more ill when he arrived in Nebraska and he did not survive.

Doctors have said early treatment increases the chances of surviving the virus.

Few details have been released about the latest patient. Hospital officials said he or she would have to agree to disclose any information.

The World Health Organization estimates that roughly 8,000 people have died from the Ebola outbreak in West Africa that began about a year ago. The epidemic has been centered in the countries of Sierra Leone, Liberia and Guinea.