Where tests are available, affordable, and feasible, they may be used to diagnose symptomatic infections or screen for asymptomatic infections. Several high-income countries recommend Paclitaxel purchase screening young women annually for chlamydia, based on evidence that screening reduces the risk of PID [38] and [63]. Screening pregnant women for syphilis is recommended in virtually

all countries [64]. Several reviews have summarized the efficacy of individual STI prevention interventions [65], [66], [67] and [68]. Implementation of STI control programs requires not only providing availability and access to these interventions, but also ensuring effective scale-up and sustainability for maximal population impact. The public health approach to STI control has had clear successes, for example, syphilis and gonorrhea infections have decreased dramatically IPI-145 ic50 among general populations of several countries with ample resources for STI control [69] and [70]. However, the gains have not been universal across all infections and all settings. Several important behavioral, biological, and implementation

factors influence the potential prevention impact of available interventions (Fig. 2), and are discussed below. Several factors can influence the effectiveness of behavioral primary prevention efforts. Consistent and correct condom no use reduces the transmission risk of virtually every STI [65], and some countries have documented declines in STI incidence in concert with implementation of counseling promoting condom use [71]. However, there have

been limits to how much progress has been made with condom promotion as the main primary prevention measure for most STIs, especially among young people. Cultural factors impact not only the acceptability of condom use, but also the comfort level with discussing sexual practices and the gender and number of partners and providing STI-related education. In addition, although several randomized trials have demonstrated that behavioral interventions can reduce STI acquisition, none of these assessed sustainability of behavior change past one year [68], which is a key factor in determining long-term impact [72]. Finally, sexual networks reflect how individuals in a population are linked through sexual relationships and thus the pathways through which STIs can be transmitted. In many populations, individual behavior may be less important than network risk, that is, the risk of the individual’s sex partner or STI prevalence in the community [16] and [72]. The vast majority of STIs cause few or no symptoms but can still lead to harmful reproductive sequelae, especially among women. Thus, the standard STI control approach based on symptomatic case management misses the greatest burden of STIs from the outset.