SYDNEY - Australian health authorities confirmed on Thursday that a 57-year-old woman was being assessed in a Queensland hospital for the deadly Ebola virus.

Chief Queensland health officer Jeanette Young told a press conference that the woman recently returned from Sierra Leone, where she has been working in a hospital treating Ebola victims.

Young said the woman had been in home quarantine since she returned on Saturday and had "not been out in the community."

The nurse developed a "low-grade fever" on Thursday morning and went to Cairns Hospital. Test results are expected to be available on Thursday evening or Friday afternoon.

Young said the people who were traveling on the plane with her were not at risk because she had not yet shown any symptoms.

"I am treating it as if it was (Ebola) ... because there is potential and that's why we're treating it so seriously," she said.

"The risk of infection is extremely low unless there has been direct exposure to the bodily fluids of an infected person or animal such as vomit, blood or diarrhea," she added.

The hospitalization follows three previous cases in Australia, one involving a Perth man, another a baby who had returned to Melbourne from west Africa, and another man who returned to Queensland from the Democratic Republic of Congo. All three patients have been cleared of the deadly virus.

Ebola, which was discovered in 1976, has killed 3,431 people and infected 7,470 people since the outbreak in West Africa in March, the World Health Organization said in its latest report.

Its symptoms include fever, muscle pain, vomiting and bleeding, and can appear as long as 21 days after exposure to the virus.