A Nigerian woman resident in Italy has been hospitalised with symptoms that have led doctors to fear she may be the country's first case of someone contracting the Ebola virus.

The woman, who had recently returned from a visit to Nigeria, has been hospitalised in Ancona and was undergoing tests in a specialist unit to establish whether she has contracted the virus which has killed more than 2,000 people since the start of the year.

"She is presenting with symptoms that could be those of Ebola," a spokesman for the local authorities in the Le Marche region said.

West Africa has been hit this year with the worst outbreak of Ebola ever seen.

Meanwhile, a fourth Ebola patient is expected to arrive in the United States from West Africa and be admitted to the same Atlanta hospital where two other people were successfully treated for the disease, according to officials.

An air ambulance carrying the new patient was scheduled to land at Dobbins Air Reserve Base, Atlanta television station WSB-TV reported.

Emory University Hospital said it could not confirm the time or give any other identifying details about the patient.

On Monday, the hospital said in a statement the patient would be treated in the same isolation unit for serious infectious diseases where US missionaries Nancy Writebol and Dr. Kent Brantly also received care for the lethal virus before being discharged last month.

Another American missionary, Dr. Rick Sacra, has also been transported to the United States from West Africa after becoming infected with Ebola in Liberia.

He is being treated at the Nebraska Medical Center in Omaha.

Medical workers have been hit hard by the epidemic, the worst since Ebola was discovered in 1976. As of late August, more than 240 healthcare workers had developed the disease and more than 120 had died, the World Health Organisation (WHO) said.

The outbreak has killed some 2,100 people overall in Guinea, Sierra Leone, Liberia and Nigeria, and has also spread to Senegal.

The WHO said on Monday that one of its doctors stationed in an Ebola treatment centre in Sierra Leone had tested positive for the disease.

That doctor was being evacuated from Freetown, the WHO said, without disclosing the person's identity or where he or she was headed.

Reuters/AFP