Every day, more than 1 million people worldwide acquire a sexually transmitted infection (STI; also called STD, for sexually transmitted disease) (WHO, 2013). “Compared with older adults,” reports the Centers for Disease Control (CDC, 2016), “sexually active adolescents aged 15–19 years and young adults aged 20–24 years are at higher risk.” Teenage girls, for example, are at heightened risk given their not fully mature anatomy and lower levels of protective antibodies (Dehne & Riedner, 2005; Guttmacher Institute, 1994).
Condoms offer only limited protection against certain skin-to-skin STIs, such as herpes, but they do reduce other risks (NIH, 2001). The effects were clear when Thailand promoted condom use by commercial sex workers. Over a 4-year period, as condom use soared from 14 to 94 percent, the annual number of bacterial STIs plummeted from 410,406 to 27,362 (WHO, 2000). When used by people with an infected partner, condoms also have been 80 percent effective in preventing transmission of HIV (human immunodeficiency virus—the virus that causes AIDS) (Weller & Davis-Beaty, 2002; WHO, 2003). Although HIV can be transmitted by other means, such as needle sharing during drug use, its sexual transmission is most common. Half of all humans with HIV (and one fourth of Americans with HIV) are women.
AIDS’ long incubation period means that many were infected in their teens and twenties. In 2012, the death of 1.6 million people with AIDS worldwide left behind countless grief-stricken loved ones, including millions of orphaned children (UNAIDS, 2013). In sub-Saharan Africa, home to two-thirds of those with HIV, medical treatment to extend life and care for the dying is sapping needed resources.
Having one sexual partner means also partnering with that partner’s past partners—any one of whom might have unknowingly transmitted an STI. Hence, the first step in preventing STIs is knowing one’s status, and sharing it with one’s sexual partner.