Craigslist ads seem to be at least partially to blame for an increase in HIV cases around the country. A recent study by professors Anindya Ghose of NYU and Jason Chan of the University of Minnesota has linked the rise of HIV cases in 33 states to people hooking up via Craigslist.

From the New York Daily News:

Cities all over the U.S. saw a nearly 16% increase in infections after the site entered the area, New York University professor Anindya Ghose and the University of Minnesota’s Jason Chan said.

The researchers linked this spike, which translated to an estimated 6,000 cases nationwide and some $62 million to $65.3 million in treatment costs, to the popularity of using the site to post personal ads for casual sex.

Ghose originally thought that the spike in HIV cases was “just a New York City thing,” but he and Chan started examining other states and found that a year after Craigslist entered, HIV cases began to rise. He accounted for the gap between the spike and Craigslist’s entry by explaining that the site needed about a year to become popular. “No matter how you sliced and diced the data, the results were consistent,” Ghose said.

(Photo: Will)