The DRC outbreak was unique, as there were at least nine different virus variants circulating in the tested patients indicative of several different spillover events from the natural reservoir to the human population [9] . In contrast, sequence data from the Angolan outbreak suggested a single introduction of MARV to an unidentified index patient and subsequent spread via person-to-person contact. The viral genomes showed a remarkably high genetic stability within this outbreak. Identical MARV genomes were isolated from patients even after two to three human to human transmissions [10] . 