( CNN ) An American health care worker who came down with Ebola while volunteering in West Africa arrived Friday at a National Institutes of Health hospital in Maryland for treatment , the NIH said . A chartered aircraft flew the patient to the United States from Sierra Leone , where the person tested positive for the deadly hemorrhagic fever while volunteering at an Ebola treatment center , the NIH said . The patient was in serious condition Friday , the NIH said . Details about the patient 's identity were n't released . The patient is the second with Ebola admitted to the NIH hospital . Nina Pham , a nurse at Texas Health Presbyterian Hospital Dallas , was admitted to NIH in October after she contracted the disease while treating Liberian national Thomas Eric Duncan . Pham recovered and was released free of disease . Duncan died . Nurse who contracted Ebola sues hospital company . NIH is one of only four hospitals in the United States that have biocontainment units and has been practicing for years to treat a highly infectious disease such as Ebola . More than 10,000 people have died in a West Africa epidemic of Ebola that dates back to December 2013 , according to the World Health Organization . Most of the deaths have been in the countries of Guinea , Liberia and Sierra Leone . Ebola is spread by direct contact with the bodily fluids of an infected person . CNN 's Athena Jones and John Newsome contributed to this report .
American was flown from Africa to Maryland hospital . CNN has one of only four U.S. hospital biocontainment units .