Patterns of sex partner recruitment are diverse; have changed over the past few decades; are associated with rates of formation and dissolution of sex partnerships, and may be associated with differential risk for acquiring sexually transmitted infections (STIs) and HIV infection. During earlier times, people met sex partners at work, school and church; in the neighbourhood; through friends and acquaintances; or on the street and/or in the brothel, massage parlour, etc.1 More recently, under the influence of technological developments, formation of new social ties has become faster and more diverse; hundreds of meet-ups are announced in local areas every week. Formation of sexual ties followed a similar pattern. Recruitment of sex partners through personal ads in newspapers,2 which was a relatively new mode of meeting partners in the late 1980s and early 1990s, has mostly been replaced by internet-based searches. In January 2009, a Google search based on the words “find sex partner on web” yielded 1 050 000 results; options included “local moms looking for younger men”, “one night stand” and “find a naughty partner for tonight”.

In theory, to the extent that a particular partner recruitment approach results in: (1) faster formation of new ties; (2) greater likelihood that infected individuals hook-up with uninfected individuals; and (3) greater numbers of individuals participating in sex-partner recruitment, holding everything else constant, it would be associated with faster spread of infection in the population. At the individual level, a particular sex-partner recruitment approach would be associated with a higher risk of STI acquisition if it increases the likelihood of “hooking-up” …