Persons with Both Main and Other Partners

thors acknowledge Louis Latour and the staff of the health department in which the study was conducted for assistance in data collection, and Gary Koch for consul-tation on statistical methods. More than 600,000 Americans havedeveloped AIDS since the begin-ning of the epidemic, and many of them contracted HIV through sexual con-tact with an infected partner. The propor-tion of infected women who acquired the virus through sexual activity with an in-fected man has risen steadily, and in 1996, it exceeded the proportion infected through injection-drug use (40 % vs. 35%). Among men, sexual contact with an infected male has been the most common mode of trans-mission throughout the epidemic, ac-counting for 59 % of infections.1 Given the importance of sexual contact in the spread of HIV among both men and women, it is imperative to understand the variability of sexual behaviors that put people at risk. Having multiple sex partners may in-crease an individual’s chances of coming into contact with a partner who is infect-ed. However, it does not necessarily in-crease the risk of acquiring a sexually transmitted disease (STD), as consistent and correct use of condoms can lower th