Ebola Outbreak Killing 70 Percent of Victims

The organisation's assistant director-general Dr Bruce Aylward said on Tuesday that the death rate was higher than the official 50 percent rate and that "a lot more people will die" if the West Africa outbreak was not stopped.

"What we're finding is 70 percent mortality," said Aylward, adding that he had a "working forecast" of 5,000 to 10,000 new cases a week by December to guide the international response.

"It's been running at about a thousand cases a week now for about three to four weeks," he said. "The labs sometimes can't keep up with the amount of specimens they're getting."

WHO figures released on Tuesday show 8,914 confirmed cases and a total of 4,447 people dead. However, the organisation has said several times that the tallies are unreliable due to difficult recording conditions and workload.

Sierra Leone, Guinea and Liberia have been hardest hit, Al Jazeera reported.

"There are this many cases that we're aware of, this many deaths that have been reported to us, but that doesn't mean you divide one by the other and get how many this disease kills," Aylward said.

"To get that number, you need to take a bunch of people, follow them right through the course of their disease, and understand how many survive. That subset of people, who we know were sick, and we know their final outcome, what we're finding is 70 percent mortality, it's almost the exact same number across the three countries," he said.

Aylward said that the WHO needed to isolate 70 percent of cases within two months to contain the outbreak.

"Every time you isolate another patient, every time you have a safe burial, you're taking some of the heat out if this outbreak," said Aylward. "But this is Ebola. This is a horrible, unforgiving disease. You've got to get to zero."

In Berlin, a UN medical worker infected with Ebola in Liberia has died. The St Georg hospital in Leipzig said on Tuesday that the 56-year-old man, whose name has not been released, died overnight of the infection.