Internet’s Dirty Secret : Assessing the Impact of Online Intermediaries on HIV Transmission

Online platforms offer access to a larger social group than is generally available through offline contacts, making the internet an emerging venue for seeking casual sex partners. The ease of seeking sex partners through classified ad sites may promote risky behaviors that increase transmission of STDs. In this paper, using a natural experiment set up, we investigate whether the entry of a major online personals ad site, Craigslist, increases the prevalence of HIV over a 10 year period from 1999 to 2008 across 33 states in the United States. After controlling for extraneous factors, our results suggest that the entry of Craigslist is related to a 15.9 percent increase in HIV cases. Our analysis suggests that the site entry produces an average of 6130 to 6455 cases of HIV infection in the U.S. each year, mapping out to $62 million to $65.3 million in annual treatment costs. In addition, the analyses reveal that non-market related casual sex is the primary driver of the increase in HIV cases, in contrast to paid transactions solicited on the site (e.g., escort services and prostitution) which has a negative relationship with HIV trends. These findings are essential to the understanding of the social routes through which HIV transmission takes place and the extent to which site entry can influence HIV trends. Implications for healthcare practitioners and policy makers are discussed