It has emerged that a Texas nurse being treated for Ebola may have shown symptoms up to three days before being diagnosed.

A spokesman for the Centers for Disease Control and Prevention (CDC) said it is expanding its investigation to include passengers on a Friday flight from Dallas to Cleveland that Amber Vinson was on.

The 29-year-old was visiting family in the Akron area last weekend before flying on Monday from Cleveland back to Dallas before being diagnosed.

CDC officials are already trying to track down 132 passengers on the Monday flight.

A second nurse who contracted the disease at the same Dallas hospital is now being moved to a federal facility in Maryland.

Officials have released a video showing Nina Pham speaking to her doctor, Gary Weinstein, from her hospital bed in the city's Texas Health Presbyterian Hospital before the move:

Fellow nurse, Brianna Aguirre, who had been helping to treat Ms Pham, has spoken publicly about what she says were substandard safety procedures inside the Texas hospital.

He explained how "the most disturbing things I saw were breaching of basic infection control principles. I saw people who were supposed to be in charge, the CDC infection control department, telling nurses, telling doctors to do things that were not safe"

Travel ban

US officials are reviewing whether to issue a ban on travel from West Africa because of the Ebola outbreak, as a congressional oversight panel called for such a measure.

Federal Aviation Administration chief Michael Huerta said: "We are all working together to assess this on a day-to-day basis."

On Capitol Hill, House Energy and Commerce subcommittee chairman Tim Murphy urged an "immediate ban" on nonessential travel from Guinea, Liberia and Sierra Leone.

US House of Representatives Speaker John Boehner, the top Republican in Washington, urged a travel ban on Wednesday.

President Barack Obama has said he does not have a "philosophical objection" to imposing a travel ban from Ebola-afflicted West Africa.

But he said experts tell him it is less effective than measures already in place, insisting a ban could result in people trying to hide where they are coming from and making them less likely to be screened.

Mr Obama also said he may appoint an additional person to lead the Ebola response in the US.