thermore, most of the female illicit drug users were commercial sex workers, suggesting an overlap between HIV epidemics among sex workers and illicit drug users. HIV infection associated with illicit drug use has been reported in other areas of sub-Saharan Africa as well, including Mauritius, Kenya, and South Africa.

Unprotected Sex

Unprotected sex is a key factor in the persistence of sexually transmitted diseases as a major public health problem worldwide (see Box 3-8). Today, more than 25 STDs are recognized (McIlhaney, 2000). According to recent reports, 12 to 15 million Americans, including 3 million teenagers, are infected with STDs every year (American Social Health Association, 1998; IOM, 1997).

STDs are a major problem among adolescents. Several national surveys have indicated that sexual activity among American teenagers has not changed dramatically over the past decade; nearly half of all high school students have engaged in sexual intercourse by the time they graduate (CDC, 2002g). While condom use among teenagers increased significantly in the 1990s, about 40 percent still report no condom use during last sexual intercourse. Moreover, teenagers tend to have serial monogamous sexual relationships that are short-lived, thereby increasing their exposure to multiple partners and their risk of contracting STDs (Overby and Kegeles, 1994).

Teenagers are not alone in their attitudes about risky sexual behaviors, however (see Box 3-9). More than 50 percent of men who have sex with men (both HIV-positive and HIV-negative) who reported having anal sex also reported having unprotected anal sex (Ostrow et al., 2002), a trend that appears to have been increasing since 1994 (Chen et al., 2002b; Katz et al., 2002). In another study, nearly one-third of HIV-infected men who were interviewed reported having unprotected vaginal or anal sex within the past year (Simon et al., 1999).


A wealth of technological advances occurring over the past century— from modern antibiotics to organ transplants to pasteurization of food products—have greatly improved health and well-being, added years to life expectancy, and eliminated many diseases that were prevalent in the nineteenth century, including typhoid, scarlet fever, and brucellosis. However, technological and industrial advances often come at a price. New infectious diseases have emerged as a direct result of changes in technology and industry; these include Legionnaires’ disease (air-conditioning cooling towers),

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