Andrew Papachristos speculated that if gun violence were a disease, it would spread along a predictable path, with a social contagion acting as a viral pathogen might, reports Jessica Wapner. Expanding on this hypothesis, Papachristos, a Yale University sociologist who studies crime, figured that outbreaks of gun violence would occur among groups of people who knew each other and subjected them to a traditional epidemiologic study.
“Papachristos postulated that subjecting gun violence to a traditional epidemiologic study would reveal whether it indeed behaves like a blood-borne pathogen,” says Wapner.
“Sixty-three percent of gun violence cases were due to social contagion,” according to the results, published in January in JAMA Internal Medicine. In other words, their model revealed that gunshot episodes cascaded through a network of people who knew each other, as “one victim exposes two friends, who become victims and then expose their friends,” just as a blood-borne pathogen, like AIDS or tuberculosis, would.