Genetic data confirm that the Ebola epidemic in West Africa is being spread from human to human, not through contact with infected animals.
The findings emphasize the need for better public health measures to keep the epidemic from spreading more widely among people rather than devoting more resources to tracking down animal reservoirs.
Genetic analyses also reveal that the Ebola virus strains infecting people in Guinea, Sierra Leone, Liberia and Nigeria originated in Central Africa in 2004, an international group of researchers reports August 28 in Science. The team sequenced the genomes of 99 Ebola viruses isolated from 78 patients during the first three weeks of the outbreak in Sierra Leone. Patterns of mutations in those viruses confirm epidemiological evidence that a healer who traveled to Guinea brought Ebola to Sierra Leone. Mourners at his funeral became infected and then spread the disease to others.