(Reuters) - U.S. health officials have designated 35 hospitals nationwide as Ebola treatment centers and expects to name more in coming weeks deemed capable of treating patients while minimizing risk to staff, the U.S. Centers for Disease Control and Prevention said on Tuesday.

The list includes those that have already treated patients with the virus, such as Emory University Hospital in Atlanta, and other prominent hospitals, including Johns Hopkins in Baltimore, Mayo Clinic Hospital in Minnesota, Children's Hospital of Philadelphia and New York-Presbyterian.

More than 80 percent of returning travelers from Ebola-stricken countries in West Africa live within 200 miles (320 km) of a designated Ebola treatment center, the CDC said.

"As long as Ebola is spreading in West Africa, we must prepare for the possibility of additional cases in the United States," CDC Director Tom Frieden said in a statement.

More than 6,000 people have died out of more than 17,000 Ebola cases in the three hardest hit countries of Liberia, Sierra Leone and Guinea, according to the World Health Organization.

Each U.S. hospital with an Ebola treatment center has been assessed onsite by a CDC Rapid Ebola Preparedness team, the agency said. CDC said it has conducted assessments of more than 50 hospitals in 15 states and Washington.

CDC has taken a far more active role in assessing Ebola treatment preparation after two nurses at a Dallas hospital contracted the virus while treating Liberian Thomas Eric Duncan, who later died from the disease. Both nurses recovered.

There are currently no known patients being treated for Ebola in the United States.

(Reporting by Michele Gershberg and Bill Berkrot; Editing by Jonathan Oatis)