Health workers are monitoring 82 people who had contact with a toddler who died of Ebola in Mali last week, but no new cases of the disease have yet been reported, World Health Organization spokesman Tarik Jasarevic said on Tuesday.

Three WHO officials are already in the country, having traveled to Mali a week ago to test its Ebola preparedness, and five more are arriving, Jasarevic said.

Mali became the sixth West African country to report a case of the disease, and health officials want to try to contain the virus before it can spread out of control.

It has already killed some 5,000 people in Sierra Leone, Liberia and Guinea, but Senegal and Nigeria both stopped the virus in its tracks by tracking down hundreds of people who had contact with the person who first brought it into their country and monitoring them constantly for symptoms.

The girl had traveled with her grandmother hundreds of kilometers by bus from Guinea via Mali's capital and was hospitalized in the western Malian town of Kayes on Oct. 20, but died four days later.

WHO has said the girl already started showing symptoms including fever, vomiting and blood in her stools - and was therefore contagious - before being taken to Kayes.

Jasarevic said the 2-year-old girl's grandmother was "doing OK so far", but the deadly disease can take up to 21 days to show up in a patient, so all the 82 contacts who have been traced, including 11 health workers, will continue to be monitored.

Diplomatic sources have expressed concern about the preparedness of Mali, one of the world's poorest countries, to contain an outbreak. Home to a large U.N. peacekeeping mission, the mostly Muslim country is still battling northern Islamist militants after a brief French-led war last year.

The possibility of setting up a treatment center in Kayes was being discussed, Jasarevic said, and 40 volunteers had been trained in contact tracing, which is considered one of the key defences against the fast-spreading disease.