The Ebola virus that devastated parts of West Africa over the past year did not mutate at a faster rate than in previous outbreaks, according to an international study published on Wednesday.

Contrary to research conducted early in the outbreak which suggested the virus was mutating at twice the rate previously seen, this study showed the mutation rate was only slightly higher in the West Africa epidemic - a finding experts said was reassuring.

"The results are good news for the scientists working to develop long-term solutions for Ebola, such as vaccines and treatments, as it means these... should still work against the mutated strains of the virus," said Miles Carroll, head of research microbiology services at Public Health England (PHE), the laboratory leading the work.

Ebola has killed more than 11,000 people in Guinea, Sierra Leone and Liberia in an unprecedented epidemic that began more than a year ago. New cases have declined sharply in the past few months, but the outbreak is not yet over.

Dwindling numbers of new infections have, however, made work on trials designed to test and validate potential vaccines and treatments almost impossible.

For their study, Carroll and researchers across Europe and in affected West African countries had access to data on the virus covering almost a year.

They analyzed 179 patient samples obtained by the European Mobile Laboratory, which was deployed to the epicenter of the outbreak in Guinea, to find how the Ebola virus mutated and spread.

Their analysis confirmed Ebola was introduced into the Guinean population in December 2013 at a single source, supporting theories from epidemiologists. Scientists believe it was first transmitted from a bat to a two-year-old boy.

The team also established how the virus spilled into Sierra Leone in April or early May 2014.

Looking at their results, Carroll said his team now believes one of the key factors in whether Ebola kills someone is the host's genetic makeup, rather than changes in the virus itself.

"Our next study will investigate this theory, which may lead to improved treatment options," he said.

David Heymann, PHE's chairman and a professor at the London School of Hygiene & Tropical Medicine, said the findings should be reassuring to scientists and the public "that the recent work on Ebola has been worthwhile and could soon lead to a better state of preparedness and response for the future".