The doctor was part of an NGO Emergency team in Sierra Leone REUTERS/James Giahyue

An Italian doctor has contracted the Ebola virus while treating patients affected by the deadly disease in Sierra Leone.

The doctor, whose identity has not been revealed, was working for NGO Emergency and will be repatriated as soon as possible for treatment.

He will be treated at Lazzaro Spallanzani, a special institute for infectious diseases in Rome.

Health Minister Beatrice Lorenzin said: "I want to reassure the family that our doctor is feeling well, he did not have fever or showed other symptoms during the night.

"His family has all my support and I want to assure that the Italian government will not leave our countryman alone."

Emergency said all its staff in Sierra Leone had been trained to avoid contamination.

"However no healthcare in such a serious epidemic can be considered completely risk-free," the NGO said in a statement.

"The situation in Sierra Leone is alarming: the epidemic is still widening with 100 new cases a day. According to the World Health Organisation there are more than 5,000 people with Ebola in the country but the real figures could be much higher."

Sierra Leone is one of the three west African nations, together with Liberia and Guinea, worst hit by the outbreak, which has killed more than 5,459 people since last January. At least 1,510 of the deaths have occurred in Sierra Leone.

Ebola is spread by contact with infected bodily fluids; symptoms include fever, vomiting, diarrhoea, and body aches.

The virus, dubbed by some "the new Aids", is causing growing concern worldwide, as hundreds of people are dying every day in Liberia, Guinea and Sierra Leone.

Some states in the US have imposed quarantine on all the people, including health workers, who have travelled to the Ebola-hit nations.

Other countries have also banned flights from the three nations, over growing concern that the outbreak might extend to other areas than West Africa.

Fears of contagion are also leading to a surge in racist and discriminatory attacks worldwide.