Sexually Transmitted Diseases, 2002
Cases of chlamydia, gonorrhea, syphilis, and chancroid are monitored through a mostly passive surveillance system. Minnesota Rules Governing Communicable Diseases require physicians and laboratories to report all laboratory-confirmed cases of these four bacterial sexually transmitted diseases (STDs) to MDH. Other common STDs caused by viral pathogens, such as herpes simplex virus and human papillomavirus, are not reportable.
Active surveillance for gonorrhea and chlamydia was initiated in January 2002. This process involves crosschecking laboratory-reported cases against cases reported by clinicians. Although both laboratories and clinical facilities are required to report STDs, an episode of STD is not considered a case for surveillance purposes until a corresponding case report is submitted by a clinical facility. Additionally, clinical case reports contain critical demographic and clinical information that is not available from laboratory reports. When a laboratory report is received but no corresponding clinical case report is received within 45 days, MDH mails a reminder and case report form to the corresponding clinical facility.
Although overall incidence rates for STDs in Minnesota are lower than those in many other areas of the U.S., certain population subgroups in Minnesota have very high STD rates. Specifically, STDs disproportionately affect adolescents, young adults, and persons of color.
Chlamydia trachomatis infection is the most commonly reported STD in Minnesota. In 2002, 10,107 cases (205 per 100,000 population) were reported, representing a 21% increase from 2001 (Table 3). Approximately one-third of this increase is an artifact of changes in reporting associated with the implementation of active surveillance.
Adolescents and young adults are at highest risk for acquiring chlamydial infection (Table 4). The chlamydia rate is highest among 20 to 24-year-olds (1,193 per 100,000 population), with the next highest rate among 15 to 19- year-olds (873 per 100,000). The incidence of chlamydia among adults 25 to 29 years of age (502 per 100,000) is considerably lower but has increased in recent years. The chlamydia rate among females (296 per 100,000) is more than twice the rate among males (113 per 100,000); however, this difference probably is due to more frequent screening among women.
The incidence of chlamydia infection is highest in communities of color (Table 4). The rate among blacks (1,444 per 100,000 population) is approximately 15 times higher than the rate among whites (97 per 100,000). Although blacks comprise approximately 4% of Minnesota's population, they account for 29% of reported chlamydia cases. Rates among Asians (245 per 100,000), American Indians (375 per 100,000), and Hispanics (584 per 100,000) are three to six times higher than the rate among whites.
Chlamydia infections occur throughout the state, with the highest reported rates in Minneapolis (757 per 100,000 population) and St. Paul (637 per 100,000). The incidence in the suburban metropolitan area (136 per 100,000) is similar to that in Greater Minnesota (119 per 100,000).
Gonorrhea, caused by Neisseria gonorrhoeae, is the second most commonly reported STD in Minnesota. In 2002, 3,049 cases (62 per 100,000 population) were reported, represent ing an increase of 13% from 2001 (Table 3). Approximately one-third of the increase likely is due to improved surveillance. Adolescents and young adults are at greatest risk for gonorrhea (Table 4), with incidence rates of 202 per 100,000 population among 15 to 19- year-olds, 288 per 100,000 among 20 to 24-year olds, and 163 per 100,000 among 25 to 29-year-olds. Gonorrhea rates for males (56 per 100,000) and females (68 per 100,000) are comparable. Communities of color are disproportionately affected by gonorrhea, with 50% of cases reported among blacks. The incidence of gonorrhea among blacks (745 per 100,000) is approximately 40 times higher than the rate among whites (19 per 100,000). Rates among Asians (29 per 100,000), American Indians (88 per 100,000), and Hispanics (91 per 100,000) are two to five times higher than among whites.
Gonorrhea rates are highest in the cities of Minneapolis and St. Paul (Table 4). The incidence in Minneapolis (363 per 100,000 population) is nearly twice the rate in St. Paul (207 per 100,000), ten times higher than the rate in the suburban metropolitan area (36 per 100,000), and 24 times higher than the rate in Greater Minnesota (15 per 100,000).
Surveillance data for primary and secondary syphilis are used to monitor morbidity trends because they represent recently acquired infections. Data for early syphilis (which includes primary, secondary, and early latent stages of disease) are used in outbreak investigations because they represent infections acquired within the past 12 months and signify opportunities for disease prevention.
Primary and Secondary Syphilis
The incidence of primary/secondary syphilis in Minnesota is lower than that of chlamydia or gonorrhea (Table 4). Fifty-nine cases of primary/secondary syphilis (1.2 per 100,000 population) were reported in 2002, representing a 79% increase in incidence from 2001.
Trends in the occurrence of syphilis in Minnesota are difficult to assess due to the relatively low number of cases. However, the number of cases of early syphilis increased significantly in 2002, driven by an increase in syphilis cases among white men who have sex with men (MSM). Eighty-two cases of early syphilis (primary, secondary, and early latent stages) were reported in 2002, compared to 49 cases in 2001. Of the 82 early syphilis cases in 2002, 70 (85%) occurred among men; 56 (80%) of these men reported having sex with other men. Almost half (45%) of the MSM diagnosed with early syphilis were co-infected with HIV. Similar increases in syphilis among MSM have been observed in other parts of the U.S.
One case of congenital syphilis (1.5 per 100,000 live births) was reported in Minnesota in 2002 (Table 3).
Chancroid continues to be very rare in Minnesota. No cases were reported in 2002.