A Cairns nurse who was hospitalised on Thursday has tested negative to the deadly Ebola virus, authorities say.

Sue Ellen Kovack, 57, presented herself to the Cairns Hospital on Thursday afternoon after complaining of a fever. Three days earlier she returned from a month-long volunteering stint in Sierra Leone treating Ebola hospital victims.

In a statement, Queensland Health chief health officer Dr Jeanette Young said Ms Kovack would remain under observation for at least another 24 hours.

"This is a necessary precaution given the patient has been to West Africa and has had a fever within the incubation period of 21 days. For the sake of her health and to follow due diligence, we want to be sure she is clear of Ebola virus disease as well as any other disease."