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The spread of the Ebola outbreak is accelerating, with more cases reported in the past week than any other week since the current crisis began, the World Health Organization said Friday.

The latest west African country to be hit was Senegal, which reported its first case on Friday, according to the Associated Press.

Senegal's minister of health, Awa Marie Coll Seck, told reporters that a man from Guinea was confirmed to have the virus, the AP reported. Guinea, Liberia and Sierra Leone have seen the bulk of the cases, while Nigeria has reported a smaller number.

The total of confirmed cases in just the past week exceeds 500, WHO said.

More than half of the 3,000 people confirmed to have been infected have died, and the WHO issued a bleak assessment Thursday projecting that as many as 20,000 people could get Ebola before the epidemic is contained. The WHO has also said that the number of actual cases could be two or four times the number that are officially confirmed.

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