Mass psychogenic illness, commonly known as mass hysteria, has made a comeback in recent years. Several high-profile outbreaks have occurred recently, most notably in Le Roy, N.Y., where 18 girls at a high school came down with a series of mysterious ticks in 2011.

Why the return? Some experts point to social networks such as Facebook, saying they make it easier to transmit the disease. While most cases of mass hysteria are localized, adding social networking sites to the mix means such outbreaks may grow.

According to Robert Bartholomew, a New Zealand sociologist, more such outbreaks are inevitable” He says, “It’s just a matter of time before we see outbreaks that are not confined to a single school, factory or region, but covering a disperse geographical area and causing real social and economic harm.” (The Atlantic)

Paul Asay has covered religion for The Washington Post, Christianity Today, Beliefnet.com and The (Colorado Springs) Gazette. He writes about culture for Plugged In and wrote the Batman book God on the Streets of Gotham (Tyndale). He lives in Colorado Springs with wife Wendy and his two children. Follow him on Twitter.