Scientists are using mutations of the Ebola virus to track the deadly outbreak's origins.
In study published in the journal Science, researchers worked backwards, tracking Ebola's 300 mutations to determine where the illness was first detected and where it has spread.
The scientists identified the funeral of a traditional healer in Central Africa as the source from which of two different strains of Ebola spread into Sierra Leone. A third strain later appeared in the West African country.
Researchers say the new findings will help create accurate diagnostic tests for Ebola, whose symptoms often closely resemble that of other infections causing high body temperature.
The latest Ebola outbreak has infected approximately 3,000 people so far killing about half of them, including five of the authors of the study before it was published.