TABLE 2 Microenvironments affecting STD patterns




Vaginal flora and acidity (pH)

Cervical ectopy


STD coinfection

Cervical mucus

HIV infection


Cervical patency

Prior STD exposure





Seminal/prostatic fluid?


changing disease patterns biologically as well as epidemiologically. Decreases in the age of menarche, a manifestation of the hormonal microenvironment, have been documented (22, 23). Finally, competing factors that influence the immunological microenvironment, such as pregnancy, HIV infection, and prior exposure to STDs, can also be traced over time in some populations.

The Behavioral Personal Environment

Changes in sexual behaviors have been one of the primary engines driving changing patterns of STDs, including HIV infection (Table 3). Steady decreases in age of first sexual intercourse and concomitant increases in premarital sexual activity have been documented repeatedly both in the United States and abroad (21, 24, 25). Data from the National Survey of Family Growth, for example, indicate that the percentage of 15- to 19-year-old American women reporting premarital intercourse almost doubled from 28.6% in 1970 to 51.5% in 1988 (26). Although increases were greatest among younger White adolescents, the proportion of Black women reporting premarital sexual activity was higher than the proportion of White women for each age group and year examined. This trend is particularly disturbing because early age of

TABLE 3 Personal environments affecting STD patterns

Sexual behaviors

Substance-use behaviors

Health behaviors

Age at coital debut

Intravenous drug use

Condom use

Number of sex partners

Crack cocaine

Pill and IUD use

Commercial sex

Exchange of sex for drugs

Vaginal douching

Sexual practices

Alcohol use




Early health-care utilization



Compliance with therapy



Provider screening

IUD, intrauterine device.

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