Scientists are investigating minorities, but it's not how it sounds. So-called "super-spreaders" are a small group of people who, for whatever reason, turn out to be the major driver behind the spread of diseases, and scientists report in the Proceedings of the National Academy of Sciences that super-spreaders are more responsible for the Ebola epidemic in West Africa than previously thought. So far they know a few things; Ebola super-spreaders tend to be younger than 15 or in the 40-to-55 age range, for instance. In applying a mathematical model to cases in and near Freetown, Sierra Leone, researchers from Princeton and Oregon State University mapped out a transmission network and ended up with this estimate: Just 3% of sufferers were responsible for 61% of infections, reports the Washington Post.
While most cases exhibited short infection periods and didn't infect many others, "a small number had longer infectious periods and generated more infections," one researcher tells the BBC. Now the big question is what makes these people so prone to infect others? It's possible that the major factor is behavioral, with super-spreaders tending to be caregivers who are in more contact with sick people with weakened immune systems. In that case, researchers say the better question might be, "What are the scenarios where super-spreading might occur?" The researchers write that if super-spreaders had "been identified and quarantined promptly" during the 2014-2015 Ebola outbreak, roughly 17,500 of the 28,600 infections might have been prevented. There were about 11,300 deaths. (These are some of the deadliest viruses known to man.)