Diseases - Sexually Transmitted Diseases

The nearly 60-year history of four major sexually-transmitted diseases shows that STDs have a cyclical pattern — produced by a complex interaction between bacterial/viral adaptations, medication, cultural patterns, economics, and demography.

Chlamydia, a bacterial infection of the genitals, is a disease of long standing but was not one of the "notifiable" diseases until 1985 — hence historical data on chlamydia are not available for earlier years. HIV/AIDS, which appears on the graphic for the first time in 1989, was first diagnosed in the United States in 1981. The name dates to 1982. Like Legionnaire's disease, which appeared in 1976, it is a newcomer. Epidemics are required to draw attention to the causative agents before diseases became classified.

First, some perspectives. HIV/AIDS has the fewest cases per 100,000 population among the STDs, but it is causing a large number of deaths. In 1999, AIDS resulted in 14,802 deaths, up from 13,426 in 1998. By contrast, syphilis, with about the same number of cases in 1998, produced 45 deaths. Gonorrhea, with a much larger number of cases, only produced 4 deaths in 1998, chlamydia none. AIDS has no cure. The other STDs are curable — although the future is less certain, as we shall see.

In the context of a presentation on social trends and indicators, three issues are worth noting about STDs: (1) anti-bacterial/viral medications appear to have a wear-out factor (bacteria and viruses develop new, resistant strains); (2) sexual behavior patterns have a major influence on who falls prey to a sexually transmitted disease; (3) populations that do not actively seek medical help — for cultural or economic reasons — experience a higher incidence of STDs because they pass on the diseases to more people.

The pattern of cases of gonorrhea is an illustration of the first two issues. In the 1970s, varieties of the disease-causing bacterium, Neisseria gonorrhea, began to occur. Incidence then began to grow. The downturn in cases did not take place until the use of variant treatments came to be introduced. The period of case-expansion also coincided with changes in sexual behavior, especially in the black population. Blacks became sexually active at increasingly younger ages. Gonorrhea is associated with young people who have multiple partners, do not use condoms, and are slow to seek medical help. Two trends, one bacteriological, one social/demographic, caused a rise in cases.

There are indications that this pattern may repeat. We may be entering a period when more and more strains of bacteria develop resistance to the tried-and-true antibiotic of the 20th century, penicillin. Periods of sexual freedom/license cause peaks in STD cases.

The black population is much more subject to STDs than other racial groups as shown by the following table. This result is traceable to different behavioral patterns — sexual and health-care seeking.

Percent of Cases by Race, 1999

Indian	Asian	Black	White	Unknown
AIDS	0.4	0.8	48.5	32.8	17.5
Chlamydia	1.3	1.4	34.8	20.9	41.6
Gonorrhea	0.5	0.5	61.4	11.4	26.3
Syphilis	0.8	0.6	73.0	15.2	10.4

Considering the relatively small size of the black population, these data show very high STD rates in the black community — 12% of the population, 61% of gonorrhea cases, for instance.

Even the STDs that do not kill have significant negative consequences for the affected person. Third, final-stage syphilis can cause coronary heart disease. Gonorrhea is a common cause of pelvic inflammatory disease (PID) in women. PID can cause infertility, damage to the Fallopian tubes, and increases the risk of pregnancies outside the womb (ectopic pregnancies). Babies born to women with gonorrhea may catch the disease during delivery, may die of blood infections, and may go blind. In men, untreated gonorrhea can lead to infertility and urinary difficulties. The disease can affect the blood and the joints and is then life threatening. Among the diseases that must be reported to the government, chlamydia produces the most cases of any disease, the vast majority of those affected being women. It produces the same problems as gonorrhea and often appears in the same person. The disease can cause pneumonia and lead to blindness. Approximately 30% of women do not have symptoms, which endangers their babies. Chlamydia can cause premature labor and delivery, hence low birth weight, hence infant mortality.

Source: Centers for Disease Control and Prevention. Data for 1999 and HIV/AIDS data from Summary of notifiable diseases, United States, 1999. MMWR 1999; 48 (No. 53). Data from 1941 through 1993: Online. Available: http://wonder.cdc.gov/wonder/STD/OSTD3202/Table_1.html.