EXUALLY TRANSMITTED INFECtions (STIs) are important cofactors in the human immunodeficiency virus type 1 (HIV-1)/AIDS pandemic. In HIV-infected individuals, not only may symptomatic and asymptomatic STIs enhance sexual transmission of HIV-1 by increasing virus shedding from the genital tract, 1-3 but at the same time HIV-1 infection itself increases susceptibility to STIs. 4 There is also considerable evidence that STIs may increase HIV-1 susceptibility in uninfected individuals, 5,6 although differentiating cause from effect is more difficult in this situation. 7 Prevention or control of STIs as a strategy for preventing HIV-1 transmission has met with mixed success. Improved syndromic management of STIs reduced HIV-1 incidence in com-munities in Mwanza, Tanzania, 8 but in Uganda neither a similar strategy nor antibiotic mass-treatment of whole communities had an impact on HIV-1 Author Affiliations and Members of the Kibera HIV Study Group are listed at the end of this article.