Last Updated Mar 12, 2015 6:19 PM EDT
An American healthcare worker has tested positive for the Ebola virus in Sierra Leone and is being flown back to the United States for treatment, the National Institutes of Health said Thursday.
The worker, who was not identified, had been volunteering at an Ebola treatment center in Sierra Leone, one of the West African nations hardest hit by the epidemic.
The NIH said the patient will be transported in isolation on a chartered jet, and is expected to arrive Friday.
The patient will be treated at the NIH Clinical Center's Special Clinical Studies Unit in Bethesda, Maryland, a specially-designed facility with a high-level medical isolation unit staffed by specialists in infectious diseases and critical care.
Word of the latest U.S. Ebola patient came as the World Health Organization marked a grim milestone in the epidemic. It announced Thursday that the virus has now killed more than 10,000 people since the outbreak began last year. Almost all of the victims have been in the three West African nations of Guinea, Liberia and Sierra Leone.
WHO reported last week that Ebola remains "widespread" in Sierra Leone and more cases are still occurring in Guinea. However, Liberia has been making strides in controlling the disease and released its last known Ebola patient from the hospital on March 5.