The American healthcare worker who contracted Ebola while volunteering in Sierra Leone, has improved to serious condition at the National Institutes of Health (NIH).
The patient, who has not been identified, was evacuated from Sierra Leone on March 14 and brought to the NIH's Clinical Center in Bethesda, Maryland just outside Washington for treatment.
"The status of the patient with Ebola virus disease being treated at the NIH Clinical Center has improved from critical to serious condition," the NIH said.
The medical charity Partners in Health said the patient is a clinician who worked in Sierra Leone, which along with Liberia and Guinea is struggling to emerge from the worst Ebola outbreak in history.
The NIH's clinic is equipped with state-of-the-art isolation facilities and is staffed with infectious disease and critical care specialists.
The NIH is the premier US medical research center in the United States.
An American nurse, Nina Pham, was treated at the clinic after she was infected with the Ebola virus at a Texas hospital by a Liberian, Thomas Eric Duncan, who had initially been misdiagnosed.
Pham was declared free of the Ebola virus on October 24, but Duncan died.
More than 10,000 people have died of the virus since the outbreak was identified in early 2014.