GENEVA — West Africa could face up to 10,000 new Ebola cases a week within two months, the World Health Organization warned Tuesday, adding that the death rate in the current outbreak has risen to 70 percent.WHO assistant director-general Dr. Bruce Aylward gave the grim figures during a news conference in Geneva. Previously, the agency had estimated the Ebola mortality rate at around 50 percent overall. In contrast, in events such as flu pandemics, the death rate is typically under 2 percent.Acknowledging that Ebola was “a high mortality disease,” Aylward said the U.N. health agency was still focused on trying to get sick people isolated and provide treatment as early as possible.He told reporters if the world’s response to the Ebola crisis isn’t stepped up within 60 days, “a lot more people will die” and health workers will be stretched even further. Experts say the epidemic is doubling in size about every three weeks.WHO raised its Ebola death toll tally Tuesday to 4,447 people, nearly all of them in West Africa, out of more than 8,900 believed to be infected. Aylward said calculating the death rate means tracking the outcomes of all possible patients — a complicated process since the numbers of cases are substantially underreported and much patient data is missing.