Specialist aid workers who return to Australia from Ebola-affected regions could soon be required to stay near capital cities for the incubation period.

Health authorities are taking an “extremely cautious” approach towards a far north Queensland nurse cleared of having Ebola virus by initial tests, saying she isn’t out of danger yet.

The case of 57-year old nurse Sue-Ellen Kovack, who recently returned to Cairns after a month-long deployment to Sierra Leone with the Red Cross, could trigger a change in national infectious disease guidelines.

Ms Kovack has returned negative initial results but will be monitored in Cairns because she is still within the 21-day incubation period of Ebola.

“If she’s got the infection, she’ll get sicker,” Queensland’s chief health officer Dr Jeannette Young told reporters on Friday.”

“At the moment, she’s getting better.”

Ms Kovack’s “low-grade” fever, which prompted her to present to authorities on Thursday morning, had resolved overnight.

But she was still showing other symptoms, Dr Young said.

“She’s got a sore throat and is feeling generally a bit unwell, which is a sign of so many other diseases.”

Dr Young again sought to reassure the public that Ebola is a very difficult virus to transmit.

A person can only catch the virus by coming into contact with secretions of an infected person, she said.

Ms Kovack returned to Australia via Casablanca and Dubai, then made her way through Perth and Melbourne to Cairns.

But Dr Young said there was no risk to other passengers because Ms Kovack could not have possibly transmitted the disease.

“We’ve had confirmation of that, the viral load was so low yesterday that it couldn’t be detected.”

Dr Young said she was satisfied with current guidelines on handling specialist aid workers who return from ebola-affected regions, but she said there was one area for improvement.

In future, volunteers may be required to stay in capital cities, close to testing facilities, during the incubation period.

“That delay, from yesterday one o’clock when the blood was taken to four o’clock this morning when I got the result, is fairly lengthy,” she said.

“It doesn’t change anything that happened, everything that was done with this nurse was done absolutely perfectly.”

She rejected suggestions from federal MP Bob Katter that Ms Kovack had put fellow Australians at risk despite her noble humanitarian intentions.

“When we think about it, she knows more than anyone what are the risk factors for Ebola virus disease, what are the symptoms, what you need to do and what you need to look out for,” she said.