The 2014-16 Ebola virus epidemic that ravaged Western Africa, killing thousands, was the largest in history. An analysis of the epidemic found that not all individuals played an equal role in spreading the deadly infectious disease—just 3 percent of patients caused more than 60 percent of infections in other people. “Superspreaders” have also been implicated in other outbreaks, including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).