Sexually Transmitted Diseases, 2000
Laboratory-confirmed infections of chlamydia, gonorrhea, syphilis, and chancroid are monitored by MDH through a passive, physician- and laboratory-based surveillance system. Other common sexually transmitted diseases (STDs) caused by viral pathogens, such as herpes simplex virus and human papillomavirus, are not reportable conditions. Population estimates used to calculate rates for a given year correspond to the prior year; for example, 2000 rates are calculated using 2000 case data and 1999 population data.
Chlamydia trachomatis infection is the most commonly reported STD in Minnesota. In 2000, 8,102 cases of chlamydia infection (170 per 100,000 population) were reported. This rate represents an 8% increase compared to 1999; since 1996, the incidence of chlamydia in Minnesota has increased 44% (Figure 7, Table 4). Possible explanations for the rising chlamydia rate include increased screening, increased use of more accurate diagnostic tests, and/or increased occurrence of disease.
Adolescents and young adults are most at risk for acquiring chlamydia infection (Table 5). The chlamydia rate is highest among 20- to 24-year-olds (956 per 100,000 population), while the next highest rate is among 15- to 19-year-olds (735 per 100,000). The incidence of chlamydia among adults aged 25 to 29 years is markedly lower (418 per 100,000), and rates among older age groups are lower yet. The rate of chlamydia infection among women (242 per 100,000) is more than twice the rate among men (96 per 100,000); however, this difference primarily is due to more frequent screening among women.
The rate of chlamydia infection is highest in communities of color (Table 5). The rate among blacks (1,769 per 100,000 population) is approximately 25 times higher than that among whites (73 per 100,000 population). Although blacks comprise only 3% of the population in Minnesota, 32% of chlamydia cases occur in this subgroup of the population. The rates among American Indians (540 per 100,000) and Hispanics (652 per 100,000) are seven to nine times higher than that among whites, and the rate among Asians (314 per 100,000) is four times higher than the rate among whites.
Chlamydia infections are distributed geographically throughout the state, although incidence rates are highest in Minneapolis (684 per 100,000 population) and St. Paul (604 per 100,000) (Table 5). The rate in the suburban metropolitan area (98 per 100,000) is more similar to the rate in greater Minnesota (87 per 100,000).
Gonorrhea, caused by Neisseria gonorrhoeae, is the second most commonly reported STD in Minnesota. In 2000, 3,160 cases (66 per 100,000 population) were reported. From 1999 to 2000, the rate of gonorrhea increased 10%; increases also occurred in 1998 and 1999 (Figure 7, Table 4). Overall, the incidence of gonorrhea has increased 25% since 1997. Reasons for these increases are unknown.
Adolescents and young adults also have the greatest risk for gonorrhea (Table 5). The rate for 15- to 19-year-olds is 233 per 100,000 population, the rate for 20- to 24-year-olds is 309 per 100,000, and the rate for 25- to 29-year-olds is 180 per 100,000. Gonorrhea rates for men (63 per 100,000) and women (69 per 100,000) are comparable. Communities of color also are disproportionately affected by gonorrhea. Blacks account for 54% of cases. The gonorrhea rate among blacks (1,149 per 100,000) is 64 times higher than the rate among whites (18 per 100,000). Likewise, the rates among American Indians (123 per 100,000) and Hispanics (135 per 100,000) are seven to eight times higher than that among whites. The rate among Asians (34 per 100,000) is nearly twice the rate among whites.
Gonorrhea cases are concentrated in the core urban populations of Minneapolis and St. Paul (Table 5). The rate in Minneapolis (407 per 100,000 population) is 1.6 times higher than the rate in St. Paul (262 per 100,000), 14 times higher than the rate in the suburban metropolitan area (29 per 100,000), and 29 times higher than the rate in greater Minnesota (14 per 100,000).
Syphilis is caused by infection with the spirochete Treponema pallidum. Primary and secondary syphilis cases typically are used to assess morbidity trends because they represent recently acquired infections.
Primary and Secondary Syphilis
The rate of primary and secondary syphilis in Minnesota is low compared to rates of chlamydia or gonorrhea (Figure 7, Table 4). Only 16 cases of primary/secondary syphilis (0.3 per 100,000 population) were reported in 2000. However, the primary/secondary syphilis rate increased 50% from 1999 to 2000, and the rate of early latent syphilis increased 100% during this same time period.
The highest rates of primary/secondary syphilis occur among 25- to 34-year olds (Table 5). Men and women have similar rates of primary/secondary syphilis (0.5 per 100,000 population and 0.2 per 100,000, respectively). The primary/secondary syphilis rate among blacks (7.4 per 100,000) is nearly 75 times higher than the rate among whites (0.1 per 100,000). Eleven (69%) of 16 cases of primary/secondary syphilis occurred among blacks, and three (19%) cases occurred among whites.
Syphilis primarily is an urban disease (Table 5). Three cases of primary/secondary syphilis were reported from greater Minnesota. The remaining 13 cases of primary/secondary syphilis were distributed between Minneapolis (nine cases; 2.3 per 100,000 population), St. Paul (two cases; 0.7 per 100,000), and the suburban metropolitan area (two cases; 0.1 per 100,000).
Of the 16 cases of primary/secondary syphilis, seven were indigenous and seven were imported; whether the infection was acquired in Minnesota was unknown for two cases.
Two cases of congenital syphilis (3.0 per 100,000 live births) were reported in Minnesota during 2000. One of the cases was a foreign-born adoptee; the other case's mother received no prenatal care.
Chancroid is very rare in Minnesota; no cases were reported in 2000.
Although overall STD rates in Minnesota are low compared to many other areas of the U.S., certain population subgroups in Minnesota have very high STD rates. Specifically, STDs disproportionately affect adolescents and young adults and persons of color. Incidence rates of STDs in Minnesota are increasing overall and among certain subgroups of the population.