WASHINGTON (AFP/REUTERS) - The first person infected with Ebola in the United States is being transferred from a Texas hospital to the National Institutes of Health near the US capital, officials said on Thursday.

Nurse Nina Pham "will be coming to the National Institutes of Health where we will be supplying her with state-of-the-art care in our high-level containment facilities," Anthony Fauci, head of the National Institute for Allergy and Infectious Diseases, told a Congressional hearing.

Pham was to arrive later on Thursday at the facility located in Bethesda, Maryland, a statement from NIH said.

The facility is "staffed by infectious diseases and critical care specialists... trained in strict infection control practices optimised to prevent spread of potentially transmissible agents such as Ebola," it said.

Pham was closely involved in the care of a Liberian man, Thomas Eric Duncan, who was the first Ebola case diagnosed in the United States.

Duncan died of Ebola on Oct 8 at Texas Health Presbyterian Hospital Dallas.

Pham was diagnosed with Ebola on Oct 12 and has been in isolation at Texas Health, which said the decision to move her was made with officials at the Centres for Disease Control and Prevention.

Pham's colleague Amber Vinson was diagnosed with Ebola on Wednesday, and was immediately transported to another high-level biocontainment unit at Emory University in Atlanta.

Both worked as nurses in the intensive care unit. Duncan was admitted on Sept 28, but his Ebola diagnosis was not made until Sept 30.

Around 70 health-care workers from the hospital are under close watch for signs of infection with Ebola. The virus' incubation period is between two and 21 days.

"With many of the medical professionals who would normally staff the intensive care unit sidelined for continuous monitoring, it is in the best interest of the hospital employees, nurses, physicians and the community to give the hospital an opportunity to prepare for whatever comes next," the Texas hospital said in a statement.

Ebola is transmitted through close contact with the bodily fluids of an infected person.

Since health-care workers are at particular risk of infection, US authorities have warned that more cases are possible.

The haemorrhagic virus is spreading quickly in West Africa, and has killed more than 4,400 people in the world's largest outbreak to date.