B97352740Z.120140806181652000GR168M02.21The number of people known to have died amid the worst Ebola outbreak on record has topped 4,000, the World Health Organization said Friday. The Geneva-based United Nations agency said the virus had killed 4,033 people out of 8,399 cases over seven months in seven countries by Oct. 8. The death toll includes 2,316 in Liberia, 930 in Sierra Leone, 778 in Guinea, eight in Nigeria — and one in the United States. A separate Ebola outbreak in Democratic Republic of Congo has killed 43 people out of 71 cases. Thomas Eric Duncan, the first person to be diagnosed with Ebola in the United States, died Wednesday in Dallas. Meanwhile, Samantha Power, the U.S. ambassador to the United Nations, said Friday that Ebola infections rates are expected to climb. “In Guinea and Sierra Leone, the number of infections is projected to double every month. In Liberia, infections are projected to double every two weeks,” Power said at a General Assembly session on Ebola. Power praised countries that “have punched far above their weight.” She cited the example of Cuba, “a country of just 11 million people” that “has already sent 165 health professionals to the region and plans to send nearly 300 more.” But she also called on more countries to “step up” in the global battle against the deadly virus. “The need is growing, and it is growing fast,” Power said. –NBC News