Using craigslist messages for syphilis surveillance…

FIRST and foremost it was anonymous info gathering, no way to link anyone to anything here–anon posts were used. AND I have the authors permission and enthusiastic support in fact to share this information from his paper/poster.

The Authors: JA Fries (Computer Science Graduate Student), TY Ho (Comp Sci graduate student), PM Polgreen (his boss and assistant prof at Univ of Iowa), AM Serge.

Notes: This a referenced abstract/paper/poster but I didn’t put them in, ask me if you want them. Also, I’m shortening a lot to get the main points out.


This paper describes a novel method of conducting large scale syphilis surveillance by examining anonymous Craigslist posts by men who have sex with men (MSM). A 20th Century by the CDC showed a 39% increase in syphilis cases from 2006-2009. Majority of the increase is among MSM community. The anonymity and relative ease of finding partners on the internet has facilitated a culture of casual sexual encounters encompassing a variety of unsafe sexual practices e.g. anonymous partners, illegal drug use, unprotected sex, group sex etc… These anonymous sexual encounters make it more difficult for public health officials to notify exposed partners. Craigslist is a website specializing in online classifieds and contains a large community of casual sex participants. Our hypothesis is that a community’s rate of risky behaviour requests can be correlated to syphilis rates.


Daily craigslist RSS feeds were collected for 416 sites around the US (54,450,547 indiv posts as of 9/1/10). 2,377,449 were identified as MSM specific and coded to counties in CA. Messages were searched for key words to identify explicit requests for unprotected sex.

Alot of math, computer coding and statistics ensued (he didn’t actually say this he put the math/stats methods, let me know if you want to know)


Messages requesting unprotected sex were positively correlated with syphilis rates significant at p < 0.05.


Craigslist messages contain useful information for disease surveillance. Keyword based message classification techniques show that the rate of unprotected sex requests in MSM specific messages can function as a proxy for syphilis rates in CA at the county level.

The Research Groups website click here.

This specific project link: click here

(his current poster on syphilis that he presented should be up and he uses similar ideas/methods dealing with HIV/AIDS)