The introduction of Craigslist in Florida apparently led to a 13.5 increase in HIV incidence over a four-year period. Publishing their findings in Management Science, researchers at the University of Maryland’s Robert H. Smith School of Business determined how the launch of Craigslist in Florida affected HIV rates by analyzing data on 12 million patients from 223 Florida hospitals from 2002 to 2006, excluding those institutions with no HIV cases or that were only open for part of the study period.

Research out of the University of Minnesota published earlier this year reached a similar conclusion, finding that the site led to a 15.9 percent increase in HIV rates in 33 states between 1999 and 2008.

The University of Maryland study found that African Americans accounted for 63 percent of the new HIV cases in Florida. More of the new cases came from people not on Medicaid, indicating that the Craigslist effect, so to speak, was greater among those with higher incomes. There was no statistically significant difference in the HIV rate increase between men and women.

To read a press release about the study, click here.