PORTLAND, Ore. » Oregon health officials say a woman who visited West Africa has been hospitalized in isolation after reporting a fever and is undergoing Ebola tests as a precaution.

Officials said Friday that the woman had no known contact with anyone affected with the virus and is considered a low risk for contracting the disease.

Tri-County Health Officer Dr. Paul Lewis says the woman has been checking her temperature twice a day and developed a "persistent fever" on Friday morning. Medics wearing protective gear evaluated her and determined she should visit a hospital.

Officials have released very little information about the woman, other than to say she had recently been in Guinea, Liberia or Sierra Leone and was staying in Portland. She was taken to a hospital in the Portland suburb of Milwaukie.