WASHINGTON (AFP) - The second US health care worker infected with Ebola flew on a domestic plane from Cleveland, Ohio to Dallas/Forth Worth airport a day before her diagnosis, and health authorities said Wednesday they are seeking to interview 132 people on that flight.

The US Centres for Disease Control said the woman "exhibited no signs or symptoms of illness while on flight 1143, according to the crew", but the agency wants to speak with passengers anyway to determine if anyone is at risk.

"Because of the proximity in time between the evening flight and first report of illness the following morning, CDC is reaching out to passengers who flew on Frontier Airlines flight 1143 Cleveland to Dallas/Fort Worth Oct. 13," the CDC said in a statement.

"Passengers who may have travelled on flight 1143 should contact CDC at 1 800 CDC-INFO (1 800 232-4636)."

Ebola is transmitted by close contact with the bodily fluids of an infected person. It is not contagious until a patient begins to show symptoms such as fever, aches, vomiting or diarrhoea.

The second case of US transmission of Ebola was announced by Dallas officials on Wednesday, and follows the diagnosis on Sunday of nurse Nina Pham.

Both health care workers were infected while caring for a Liberian man, Thomas Eric Duncan, who was infected in West Africa and diagnosed in Texas where he had flown to visit family.