TABLE 1 Changing patterns of STDs

Pattern

Examples

Emergence of new organisms/etiologies

Reemergence of old STDs

Population shifts

Etiology shifts

Altered incidence of complications

Increased antimicrobial resistance

HIV, infertility, ectopic pregnancy, fetal death, low birth weight, prematurity, anogenital cancer, proctocolitis

Syphilis

HIV infection, syphilis, gonorrhea

Urethritis, cervicitis, PID

Perinatal HIV infection, congenital syphilis, PID, dysplasia

Gonorrhea, chancroid

PID, pelvic inflammatory disease.

STDs, shifts in the populations in which STDs are concentrated, shifts in the etiological spectra of STD syndromes, alterations in the incidence of STD complications, and increases in antimicrobial resistance (Table 1). Many STDs represent examples of more than one of these trends.

Exciting insights into the pathophysiology and natural history of both bacterial and viral STDs have led to the discovery of sexually transmitted etiologies for such diverse syndromes as infertility, ectopic pregnancy, other adverse outcomes of pregnancy, anogenital cancers, and proctocolitis. However, human immunodeficiency virus (HIV) is clearly the archetype of a newly emerging STD pathogen, one that has devastated the world with a fatal pandemic involving an estimated 14 million people, of whom approximately 2.5 million have developed AIDS (2). In the United States alone, it is likely that as many as a million individuals are infected with HIV, and more than 361,000 AIDS cases have been reported since 1981, when the syndrome was first recognized (3).

Despite its recent emergence, AIDS is, in addition, a prime example of a disease that is shifting to affect new populations (Figure 1). In the United States, AIDS spread first among predominantly white homosexual and bisexual men, but AIDS incidence in this population began to plateau by the early 1990s (4, 5). The second wave of the AIDS epidemic emerged among injecting-drug users (IDUs) and was concentrated among racial and ethnic minority populations. At least since 1989, however, the greatest proportionate increase in reported AIDS cases has been due to heterosexual transmission, and the majority of these cases have occurred among women (47). Between 1991 and 1992, for example, a 17% increase in AIDS cases attributed to heterosexual transmission was observed, compared with a 1% decrease in cases due to homosexual or bisexual transmission, and a 1% increase in IDU-related cases among heterosexuals. In 1992, although half of all new AIDS cases



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement