Syphilis Is Making a Comeback, and U.S. Public Health Officials Aren't Sure Why
The sexually transmitted infection is easy to treat but difficult to detect in its early stages.

It's hard to miss "SYPHILIS EXPLOSION" ads that prominently feature those capitalized words before a fiery red erupting volcano. They were plastered across BART stations in the Bay Area and billboards in Los Angeles late last year courtesy of the AIDS Healthcare Foundation, which says the campaign has already appeared in or is heading to Cleveland, Columbus, Baton Rouge, Brooklyn and other cities.

Syphilis, which can cause serious health problems if untreated, is on a troubling upswing across the United States.