By January 2011 well over 1 million cumulative cases of AIDS had been reported in the United States, and almost 600,000 people had died of the disease since it was first diagnosed in 1981. The number of people in the United States living with HIV, approximately 1.2 million, continues to increase (Tasker, 2011; Torian et al., 2011). About 20% of people in the United States living with HIV are unaware of their HIV status (Centers for Disease Control, 2011f).

Each year about 2.6 million new HIV infections occur globally and almost 34 mil­lion people worldwide are infected (Dieffenbach & Fauci, 2011; Kelland, 2011). Before 2007, United Nations officials estimated that each year about 5 million new HIV infec­tions occurred worldwide and that a total of about 40 million people were infected (UNAIDS, 2006). Recently, lower estimates of global HIV infection rates have been made based on a more accurate method for assessing worldwide HIV infection preva­lence (Cheng, 2007). While the decline in global infection rates is due largely to revised numbers reflecting better methodology, there is mounting evidence that the HIV/ AIDS pandemic is losing some of its global momentum (Brown, 2010). By the end of the first decade of the 21st century, the number of new HIV infections worldwide was nearly 20% lower than a decade earlier (Brown, 2010). The downward trend in the number of global HIV infections is the result of many influences, including a reduction of risky sexual behaviors, lower infectious risk among people undergoing antiretroviral drug treatment, and significant success in preventing mother-to-child HIV transmis­sion (Brown, 2010). The decline in HIV/AIDS may also reflect "the epidemics’ natural history, in which the annual number of new infections peaks and then declines as the disease saturates high-risk groups in the population" (Brown, 2010, p. 9).

In sub-Saharan Africa, national epidemics have stabilized or even declined slightly in several countries (Steinbrook, 2008). Nevertheless, in spite of these encouraging signs, we cannot lose sight of the fact that the pandemic continues to rage. To date, more than 25 million people worldwide have already died of AIDS, and the disease claims about 2 million lives each year (Friedrich, 2011a; Kelland, 2011). Global annual death rates caused by AIDS peaked in 2005 and decreased over the next several years, due in part to wider availability of antiretroviral drug therapy (Brown, 2010; Jaffe, 2008). Sub­Saharan Africa is estimated to be home to roughly two thirds of all people living with AIDS. The hardest hit nation, South Africa, is home to about one sixth of the world’s HIV-infected people (De Cock et al., 2011).

The number of new AIDS cases reported annually in the United States grew rapidly throughout the early 1980s, increasing by about 85% each year, and reached a peak rate in the middle of the decade. Until recently, the CDC estimated that approximately 40,000 new HIV infections have occurred annually in the United States since the early 1990s through 2007. However, recent evidence indicates that federal officials have been underes­timating the number of new HIV infections for more than a decade (Maugh, 2008). New laboratory-based procedures, which make possible improved estimation of HIV infection incidence, indicate that approximately 50,000 to 56,000 new infections have occurred each year during this period (Centers for Disease Control, 2010h; McNeil, 2011). Although the overall incidence of new HIV infections in the U. S. population has been stable for several years, the number of new cases among teenagers, women, and racial and ethnic minorities continues to rise (Guilamo-Ramos et al., 2011; Timpson et al., 2010).

Many people with AIDS were infected during their adolescent years (Balaji et al., 2008). Unfortunately, it is very uncommon for American adolescents to be tested for HIV. A recent nationwide survey found that only 12.7% of teenagers have been tested, with more females (14.7%) than males (10.9%) having had an HIV test (Centers for Disease Control, 2010h). The growing problem of HIV infection among adolescents has been attributed to a number of factors, including the following:

■ Many teenagers have multiple sexual partners, increasing their exposure to infection.

■ Many adolescents engage in sexual activity without using condoms.

■ Access to condoms is generally more difficult for adolescents than for other age groups.

■ Many adolescents do not use condoms correctly and consistently as revealed by the NSSHB (Reece et al., 2010b).

■ Teenagers have high rates of other STIs, which are often associated with HIV infection.

■ Substance abuse, which often increases risky behavior, is relatively widespread among adolescents (Freeman et al., 2011).

■ Teenagers tend to be especially likely as a group to have feelings of invulnerability (see Chapter 12).

■ On the other hand, a significant number of teenagers, nearly 15% according to a recent study, take chances and engage in risky behavior because of a strong sense of fatalism or belief they will die young (Borowsky et al., 2009).

■ Homeless youth often engage in risky sexual behavior that increases their vulner­ability to HIV infection (Rice et al., 2012).

MSM (men who have sex with men) and ethnic and racial minority groups in the United States account for a majority of the total number of AIDS cases reported since 1981 (Centers for Disease Control, 2011a; McCree et al., 2010). The higher AIDS rates among ethnic and racial minority groups might reflect, among other factors, (1) reduced access to health care, associated with disadvantaged socioeconomic status, (2) cultural or language barriers that limit access to information about strategies for preventing STIs, and (3) differences in HIV risk behaviors, especially higher rates of injection drug use.

Since AIDS first appeared in the United States, most cases have been directly or indi­rectly related to two risk-exposure categories: MSM and injection drug users. The preva­lence of HIV infection in the United States remains highest among MSM, who account for 53-59% of HIV infections in the United States (Centers for Disease Control, 2011d; Oster et al., 2011). Reported AIDS cases among MSM declined sharply and then lev­eled off between the mid-1980s and the late 1990s (Adams et al., 2005). Unfortunately, the incidence rates of HIV infection among MSM are again moving upward (Centers for Disease Control, 2011d, 2011e; D. Smith et al., 2011). This resurgence of the HIV epidemic among MSM is especially prevalent among young MSM and among MSM of color (K. Jones et al., 2008; Oster et al., 2011; Mustanski, Newcomb et al., 2011).

In recent years an HIV/AIDS epidemic has emerged among MSM in countries in the Middle East and North Africa, especially Egypt, Sudan, and Tunisia (Friedrich, 2011a).

The number of HIV infections attributed to injection drug use has declined in recent years but still remains high at roughly 9% of new HIV infections occurring annu­ally in the United States (Centers for Disease Control, 2012a).

In the United States about a third of all AIDS cases are attributable to heterosexual transmission (Maugh, 2008). Heterosexual contact has always been the primary form of HIV transmission worldwide, especially in Africa and Asia (Harris & Bolus, 2008; UNAIDS, 2006).

Over the last few years the number of women infected with HIV has steadily increased in the United States and worldwide (Harris & Bolus, 2008). In sub-Saharan Africa, women ages 15 to 24 are three to four times more likely to be infected with HIV than are young men their age (Underwood et al., 2011).

Research indicates that HIV is not as easily transmitted from women to men as it is from men to women (Shapiro & Ray, 2007). Thus the risk of becoming infected through heterosexual intercourse appears to be much greater for a female with an HIV- infected male partner than for a male with an infected female partner. One explanation for women’s greater risk during heterosexual intercourse is that semen contains a higher concentration of HIV than vaginal fluids do, and the female mucosal surface is exposed to HIV in the ejaculate for a considerably longer time than a male’s penis is exposed to HIV in vaginal secretions (Lamptey et al., 2006; Shapiro & Ray, 2007). In addition, a larger area of mucosal surface is exposed on the vulva and in the vagina than on the penis, and the female mucosal surface is subjected to greater potential trauma than is typically the case with the penis (Lamptey et al., 2006). Furthermore, some women engage in unprotected anal intercourse, a high-risk behavior because HIV transmission from an infected man to an uninfected woman is thought to be 10 times as likely with anal intercourse as with vaginal intercourse (Shapiro & Ray, 2007). In fact, receptive unprotected anal intercourse has been shown to be associated with the highest risk of HIV infection through sexual activity for both men and women (Jenness et al., 2011; Shapiro & Ray, 2007). Finally, adolescent women are especially biologically vulnerable to HIV infection because their immature reproductive tracts, especially the cervix, are highly susceptible to infection by STIs (Lamptey et al., 2006; Shapiro & Ray, 2007).

The global proportionate incidence of HIV/AIDS among women is considerably greater in Africa, Asia, and the Caribbean than in the United States. In sub-Saharan Africa—the epicenter of HIV/AIDS—about 57% of HIV infections among adults occur in women (Yount & Abraham, 2007). About 75-80% of HIV infections among African youth are of females (Tenkorang & Matick-Tyndale, 2008). It is estimated that among the 800,000 children infected with HIV each year (most in sub-Saharan African countries), about 90% of the infections result from mother-to-child transmission (Har­ris & Bolus, 2008; Stringer et al., 2008).

In developing nations, especially those in Africa, a majority of new HIV infections occur among 15- to 24-year-olds (Kim & Free, 2008). The terrible plight of Africa dur­ing these plague years is described in the following Sexuality and Diversity discussion.