Context Transmission of sexually transmitted diseases (STDs) such as human immunodeficiency virus (HIV) infection is associated with unprotected sex among multiple anonymous sex partners. The role of the Internet in risk of STDs is not known. Objective To compare risk of STD transmission for persons who seek sex partners on the Internet with risk for persons not seeking sex partners on the Internet. Design Cross-sectional survey conducted September 1999 through April 2000, Setting and Participants A total of 856 clients of the Denver Public Health HIV Counseling and Testing Site in Colorado. Main Outcome Measures Self-report of logging on to the Internet with the intention of finding sex partners; having sex with partners who were originally contacted via the Internet; number of such partners and use of condoms with them; and time since last sexual contact with Internet partners, linked to HIV risk assessment and test records. Results Of the 856 clients, most were white (77.8%), men (69.2%), heterosexual (65.3%), and aged 20 to 50 years (84.1%), Of those, 135 (15.8%) had sought sex partners on the Internet, and 88 (65.2%) of these reported having sex with a partner initially met via the Internet, Of those with Internet partners, 34 (38.7%) had 4 or more such partners, with 62 (71.2%) of contacts occurring within 6 months prior to the client's HIV test. Internet sex seekers were more likely to be men (P<.001) and homosexual (P<.001) than those not seeking sex via the Internet. Internet sex seekers reported more previous STDs (P=.02); more partners (P<.001); more anal sex (P<.001); and more sexual exposure to men (P<.001), men who have sex with men (P<.001), and partners known to be HIV positive (P<.001) than those not seeking sex via the Internet, Conclusions Seeking sex partners via the Internet was a relatively common practice in this sample of persons seeking HIV testing and counseling (representative of neither Denver nor the overall US population). Clients who seek sex using the Internet appear to be at greater risk for STDs than clients who do not seek sex on the Internet.
