In response to the recent large-scale outbreak of Ebola virus disease, a team of researchers used high-throughput sequencing to study diversity among 99 Ebola virus genomes from 78 patients in Sierra Leone. Comparison with previous outbreak strains revealed that the viruses in this epidemic are likely to have spread from Middle Africa within the past decade, followed by human-to-human transmission during the outbreak. Moreover, they found 395 mutations that are distinct to this current lineage, including 50 fixed non-synonymous mutations, which might represent possible determinants of pathogenicity and therapeutic avenues for this epidemic.