Ebola mortality rate expected to rise as outbreak runs its deadly course

 The death rate so far in the world's worst outbreak of Ebola is not as extreme as recorded in the past, but experts expect it to prove no less virulent in the end, once more victims succumb and the grim data is tallied up.

Latest figures from the World Health Organization (WHO) record 1,603 cases of Ebola in the West African outbreak and 887 deaths - giving a death rate of just over 55 percent.

That is well below the 78.5 percent average death rate over 14 past outbreaks of the same virus - called the "Zaire strain" after the former name of the Democratic Republic of Congo where it was first detected in 1976. In some outbreaks the rate was up to 90 percent, according to WHO data.

Experts say death rates for Ebola outbreaks can rise as the disease runs its course, which is what they now expect.


Ebola can take up to a month to kill its victims, said Ben Neuman, an expert in viruses at Britain's Reading University.

Already, the death rate in Guinea, where the infection was first detected, has reached 74 percent. The overall regional outbreak mortality figure is brought down by lower death rates in countries that were more recently hit: 54 percent in Liberia and around 42 percent in Sierra Leone.

Ebola has no proven cures and there is no vaccine to prevent infection, so the best treatment is focused on alleviating symptoms such as fever, vomiting and diarrhea - all of which can contribute to severe dehydration.

Patients often need oral rehydration with solutions containing electrolytes, or intravenous fluids. Severely ill patients need intensive care.

But languishing in the bottom part of the U.N. Human Development Index, Guinea, Sierra Leone and Liberia have some of the weakest health systems in the world. This, combined with porous borders, poor sanitation and local ignorance of the disease have helped its spread.

Two American aid workers who contracted Ebola while working in West Africa have been flown home for treatment are likely to have a better than average chance of survival due to higher standards of healthcare.