The logo on the cover of Sexually Transmitted Disease Surveillance, 2005 is a reminder of the multifaceted, national dimensions of the morbidity, mortality, and costs that result from sexually transmitted diseases (STDs) in the United States. It highlights the central role of STD prevention in improving health among women and infants and in promoting HIV prevention. Organized collaboration among interested, committed public and private organizations is the key to reducing STDs and their related health burdens. As noted in the report of the Institute of Medicine, The Hidden Epidemic: Confronting Sexually Transmitted Diseases,1 surveillance is a key component of our efforts to prevent and control these diseases.
This overview summarizes national surveillance data on the three diseases for which there are federally-funded control programs: chlamydia, gonorrhea, and syphilis. Several observations for 2005 are worthy of note.
In 2005, 976,445 cases of genital Chlamydia trachomatis infection were reported to CDC (Table 1). This case count corresponds to a rate of 332.5 cases per 100,000 population, an increase of 5.1% compared with the rate in 2004. Rates of reported chlamydia infections among women have been increasing annually since the late 1980s when public programs for screening and treatment of women were first established to avert pelvic inflammatory disease and related complications. The continued increase in chlamydia case reports in 2005 most likely represents a continued increase in screening for this infection, but it may also reflect a true increase in morbidity.
In 2005, the overall rate of chlamydia infection in the United States among women (496.5 cases per 100,000 females) was over three times the rate among men (161.1 cases per 100,000 males), reflecting the large number of women screened for this disease (Tables 4 and 5). However, with the increased availability of urine testing, men are increasingly being tested for chlamydia infection. From 2001 through 2005, the chlamydia rate in men increased by 43.5% (compared with a 15.6% increase in women over this period).
Data from multiple sources on prevalence of chlamydia infection in defined populations have been useful in monitoring disease burden and guiding chlamydia screening programs.
In 2005, the median state-specific chlamydia test positivity among women 15 to 24 years old who were screened at selected family planning clinics in all states, the District of Columbia, Puerto Rico, and the Virgin Islands was 6.3% (range 3.0% to 20.3%) (Figure 8).
At selected prenatal clinics in 25 states, Puerto Rico, and the Virgin Islands the median state-specific chlamydia prevalence was 8.0% (range 2.8% to 16.9%) (Figure E).
The prevalence of infection is greater among economically-disadvantaged women 16 to 24 years of age who entered the National Job Training Program in 2005 from 39 states, the District of Columbia, and Puerto Rico. The median state-specific prevalence was 9.2% (range 3.1% to 14.5%) (Figure K). Among men entering the program in 2005 from 48 states, the District of Columbia, and Puerto Rico the median state-specific chlamydia prevalence was 8.1% (range 0.0% to 14.8%) (Figure L).
The prevalence is even greater among adolescent women entering 57 juvenile detention centers; the median chlamydia positivity by facility was 14.2% (range 3.7% to 33.7%) (Table AA).
Among adolescent men entering 87 juvenile detention centers, the median chlamydia positivity was 6.0% by facility (range 0.0% to 44.8%) (Table AA).
Although these data on prevalence are not entirely comparable because of differences in the populations screened, in the performance characteristics of the screening tests, and variations in screening criteria, they provide important information on the continuing high burden of disease in the United States.
Following a 74% decline in the rate of reported gonorrhea from 1975 to 1997, overall gonorrhea rates appeared to plateau. In 2005, 339,593 cases of gonorrhea were reported in the United States, corresponding to a rate of 115.6 per 100,000 population, a slight increase from 2004 (Figure 11 and Table 1). This rate considerably exceeds the Healthy People 2010 (HP2010) target of 19 cases per 100,000 population.
As in previous years, in 2005 the South had the highest gonorrhea rate among the four regions of the country (Table 12). However, the rate in the South has declined by 17.6% since 2001, and declines have also been observed in the Northeast. Minimal change has been seen in the Midwest. In contrast, the rate in the West has increased by 35.4% from 60.2 cases per 100,000 population in 2001 to 81.5 cases in 2005.
For the fourth straight year, the gonorrhea rate in women in 2005 was slightly higher (119.1 per 100,000 population) than the rate among men (111.5 per 100,000 population) (Figure 12). As with chlamydia, rates of gonorrhea in women are particularly high in 15- to 19-year-olds, and in men, are highest in 20- to 24-year-olds (Figure 18). Although the gonorrhea rate among 15- to 19-year-olds has decreased in recent years, from 2004 to 2005 this rate increased 3.9% (Table 19). Similar to previous years, in 2005, African-American 15- to 19-year-old females had the highest gonorrhea rate of any age and race/ethnic group (2,814.0 cases per 100,000 population) (Table 20B). However, gonorrhea rates among both African-American men and women decreased from 2001 through 2005 (19.4% and 16.1%, respectively). In contrast, gonorrhea rates among both white men and women have increased between 2001 and 2005 (18.9% and 20.4%, respectively).
In 2005, data on gonorrhea prevalence in defined populations were available from several sources. These data showed a continuing high burden of disease in adolescents and young adults in some parts of the United States.
For 16- to 24-year-old women entering the National Job Training Program in 32 states and the District of Columbia in 2005, the median state-specific gonorrhea prevalence was 2.4% (range 0.0% to 6.6%).
Among men entering the program from 14 states, the median state-specific gonorrhea prevalence was 2.2% (range 0.0% to 6.1%).
Among women entering juvenile corrections facilities the median gonorrhea positivity was 4.7% (range 0.9% to 14.2%); the median gonorrhea positivity for men entering juvenile corrections facilities was 1.0% (range 0.0% to 19.0%).
Among women entering adult corrections facilities, the median gonorrhea positivity was 2.8% (range 0% to 13.8%). In men, the median gonorrhea positivity was 2.3% (range 0.0 to 11.8%) in adult corrections facilities.
Among men who have sex with men attending eight STD clinics, the median clinic urethral positivity was 11% (range 8% to 14%).
There remains considerable geographic variation in the prevalence of fluoroquinolone-resistance within the United States, at least for heterosexuals, with rates highest in the Western part of the country. In the Gonococcal Isolate Surveillance Project (GISP), a sentinel surveillance project located in 27 STD clinics throughout the United States, the proportion of isolates among men who have sex with men (MSM) that were resistant to ciprofloxacin increased again in 2005 to 29%. The overall proportion of resistant isolates among heterosexuals was 3.8% in 2005, up from 2.9% in 2004. Fluoroquinolone-resistant isolates were identified in 25 of the 27 GISP clinics but prevalence was highest in Western sites.
The rate of primary and secondary (P&S) syphilis reported in the United States decreased during the 1990s and in 2000 was the lowest since reporting began in 1941. The low rate of syphilis and the concentration of the majority of syphilis cases in a small number of geographic areas led to the development of the National Plan to Eliminate Syphilis from the United States, which was announced by the Surgeon General in 1999 and revised in 2006.2 The rate of P&S syphilis in the United States declined by 89.7% from 1990 through 2000. However, the rate of P&S syphilis has increased each year since 2001, mostly among men, but also in women for the past year. In 2005, P&S syphilis cases reported to CDC increased to 8,724 from 7,980 in 2004, an increase of 9.3%. The rate in men increased 8.5% while that in women increased 12.5%. Cases of congenital syphilis continued to decline; 329 cases of congenital were reported in 2005, down from 371 in 2004.
Although wide disparities exist in the rates of STDs among racial and ethnic groups, there has been a reduction in these differences for syphilis over the past five years. The P&S syphilis rate for 2005 among African Americans was 5.4 times the rate among whites, reflecting a substantial decline from 1999, when the rate among African Americans was 29 times greater than that among whites (Table 32B). While this has reflected decreasing rates among African Americans, it also reflects significant increases among white men during the past five years. In 2005, increases were observed among both African-American men (15.7 cases per 100,000 population, up from 13.9 in 2004) and African-American women (4.4 cases per 100,000 population, up from 4.2 in 2004). An increase was also observed among white men (3.3 cases per 100,000 population), up from 3.1 in 2004, while the rate in white women remained the same (0.3 per 100,000 population).
While syphilis elimination efforts have successfully focused on heterosexual minority populations at risk for syphilis, recent increases in syphilis among MSM and smaller increases among women and African Americans highlight the importance of continually reassessing and refining surveillance, prevention, and control strategies.
1 Institute of Medicine. The Hidden Epidemic: Confronting Sexually Transmitted Diseases, Committee on Prevention and Control of Sexually Transmitted Diseases, National Academy Press, Washington, DC, 1997.