Over 40 people known to have come into contact with her have been quarantined. The girl was being treated in Kayes town, after arriving at a hospital on Wednesday.

The child had travelled over 1,000 km from Guinea through Bamako to Kayes.

"The child's symptomatic state during the bus journey is especially concerning, as it presented multiple opportunities for exposures, including high-risk exposures, involving many people," the WHO said.

The girl's mother died in Guinea a few weeks ago and the child was then brought by her relatives to Mali.

Guinea, Liberia and Sierra Leone have seen most of the 4,800 Ebola deaths.

Mali has now become the sixth West African country to be affected by the outbreak, although Senegal and Nigeria have since been declared virus-free by the WHO.

The WHO has three experts in Mali evaluating its ability to cope with Ebola and will send at least four more experts over the next few days, spokeswoman Fadela Chaib said.

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