the technical competence of providers and adherence to infection control practices.
Various behaviors determine a person's risk of acquiring a sexually transmitted infection, thereby providing several opportunities for intervention. Primary prevention interventions stress either reducing an individual's risk of sexual contact with an infected person or decreasing the per-exposure probability of acquiring an infection. Secondary prevention efforts (discussed below) seek to decrease the duration of infectiousness for those STDs (primarily bacterial) that are amenable to treatment. Three factors in combination—the likelihood of contact with an infected person, the efficacy of per-exposure transmission, and the duration of infectiousness—are the principal determinants of the spread of sexually transmitted infection within a population (Anderson and May, 1988).
Strategies to reduce exposure to infections include encouraging a delay in the initiation of sexual activity, a reduction in the number of concurrent sexual partners, a reduction in the rate of sexual partner change, more careful selection of sexual partners, and efforts to reduce the incidence of nonconsensual sex. Strategies to reduce the per-exposure risk of infection include avoiding certain sexual practices, treatment of other RTIs, and the promotion of condoms and other vaginal barrier methods (see Table 3-4).
Delay of Initiation of Sexual Activity Delaying the initiation of sexual activity is especially important because of the enhanced biological susceptibility of adolescents to sexually transmitted infections and their consequences (Gotardi et al., 1984). Behavioral research findings also suggest that early coital debut is associated with a subsequent higher prevalence of high-risk sexual practices (Kost and Forrest, 1992). A recognition of the difficulties adolescents often face in obtaining reproductive health services (Karim et al., 1992; Flisher, Roberts, and Blignaut, 1992) is another reason to encourage this approach.
Several successful programs have been described (Coates and Makadon, 1995; Kirby et al., 1991; Howard and McCabe, 1990; Walter and Vaugh, 1993). The essential elements of success seem to be peer intervention approaches that stress autonomy and healthy decision making, and the provision of accurate information concerning sexuality, the consequences of unprotected sexual activity, and the available options for avoiding infection and unwanted pregnancy. Providing accurate information on sexuality to adolescents has not been shown to increase early