A Cairns nurse who recently returned from west Africa will remain isolated until health authorities are sure she is clear of the deadly Ebola virus.

Cairns nurse Sue Ellen Kovack will remain isolated and under close observation until health authorities are sure the 57-year-old is clear of Ebola.

As initial blood tests came back negative for the deadly virus, health authorities on Friday cautioned that Ms Kovack is not yet out of danger and will undergo further assessment over the weekend.

The warning came as screening measures were being ramped up at international airports around the nation – despite the Health Department saying the risk of an Ebola outbreak remains low – and as it emerged 11 Australians had been tested and cleared.

Meanwhile, the United Nations called for a 20-fold increase in the world’s response to Ebola, which has killed almost 3900 people in west Africa since January.

Ebola’s spillover into the United States and Europe has raised fears of a wider outbreak, and has prompted the US, Canada and Britain to also start tougher airport screening.

In Queensland, chief health officer Jeannette Young said on Friday the negative test result for Ms Kovack was good news but that the nurse would have to remain in quarantine in Cairns Hospital 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,” Dr Young said.

The Red Cross worker recently returned from a month-long deployment in Ebola-ravaged Sierra Leone, via Casablanca and Dubai, then made her way through Perth and Melbourne to Cairns.

However, authorities have moved to allay fears Ms Kovack could have spread the virus, which can only be contracted by coming into contact with secretions of an infected person.

Dr Young said she was also satisfied with current guidelines on handling specialist aid workers who return from Ebola-affected regions, but that volunteers may be required in future to stay in capital cities, close to testing facilities.

Health Minister Peter Dutton said hospitals around the country were being prepared so that they could deal with the disease in the event of it reaching Australia.

“We have put in place plans in major tertiary hospitals around the country that, if we do have a positive case, we will be able to deal with that case,” Mr Dutton said.

As of Friday, travellers arriving in Australia from west African countries will be interviewed and screened for symptoms.

Banners have been fixed in international airports to raise awareness of symptoms, and pamphlets distributed on some flights.

All border agencies have been educated by the Department of Health to identify and quarantine any passengers presenting Ebola symptoms in flights or at airports.

Very few people travel to Australia from west Africa, with no direct commercial flights from any of the affected countries.

Despite the new measures and assurances of low risk to the country, federal MP Bob Katter has ramped up his criticism of quarantine protocols.

A day after drawing flak for suggesting Ms Kovack had put the nation at risk through her “humanitarian ambitions”, Mr Katter on Friday said Australians returning from west African countries should “go to a quarantine holiday resort” until they can be cleared of the virus.

“They can have a beaut, terrific holiday there for three weeks when they come home and it will be a very nice thing for them,” said Mr Katter, whose electorate of Kennedy includes the southern area of Cairns and the Cairns airport.

Australia’s peak medical body has slammed Mr Katter’s comments.

“To strike fear into the hearts of Australians and suggest that this person has put her own ambitions above the interests of the community I think is a disgraceful comment,” AMA president Brian Owler said.