ZURICH—The number of Ebola cases reported in the current outbreak topped 10,000, the World Health Organization said Saturday, as it added a new nation to the list of countries affected by the disease.

In an update, the United Nations health agency said 4,922 people had died of confirmed, suspected or probable cases of Ebola. Almost all of the deaths were in Guinea, Liberia and Sierra Leone, the three West African countries at the center of the epidemic.

...